Replace mainWindow() with MainWindow::instance()

C++ style of accessing single instance class object.

Signed-off-by: Boris Barbulovski <bbarbulovski@gmail.com>
Signed-off-by: Dirk Hohndel <dirk@hohndel.org>

18 files changed, 104 insertions, 96 deletions

diff --git a/main.cpp b/main.cpp
index 903d8e5f9..4a3b4ea4d 100644
--- a/main.cpp
+++ b/main.cpp
@@ -48,8 +48,8 @@ int main(int argc, char **argv)
 			files.push_back( QString(prefs.default_filename) );
 	}
 	parse_xml_exit();
-	mainWindow()->loadFiles(files);
-	mainWindow()->importFiles(importedFiles);
+	MainWindow::instance()->loadFiles(files);
+	MainWindow::instance()->importFiles(importedFiles);
 	if (!quit)
 		run_ui();
 	exit_ui();
diff --git a/qt-ui/divecomputermanagementdialog.cpp b/qt-ui/divecomputermanagementdialog.cpp
index 348f93b40..c7d7fc75b 100644
--- a/qt-ui/divecomputermanagementdialog.cpp
+++ b/qt-ui/divecomputermanagementdialog.cpp
@@ -22,7 +22,7 @@ void DiveComputerManagementDialog::init()
 
 DiveComputerManagementDialog* DiveComputerManagementDialog::instance()
 {
-	static DiveComputerManagementDialog *self = new DiveComputerManagementDialog(mainWindow());
+	static DiveComputerManagementDialog *self = new DiveComputerManagementDialog(MainWindow::instance());
 	self->setAttribute(Qt::WA_QuitOnClose, false);
 	return self;
 }
diff --git a/qt-ui/divelistview.cpp b/qt-ui/divelistview.cpp
index 43f0b1c38..028b232c2 100644
--- a/qt-ui/divelistview.cpp
+++ b/qt-ui/divelistview.cpp
@@ -518,7 +518,7 @@ void DiveListView::mergeDives()
 			}
 		}
 	}
-	mainWindow()->refreshDisplay();
+	MainWindow::instance()->refreshDisplay();
 }
 
 void DiveListView::merge_trip(const QModelIndex &a, int offset)
@@ -648,10 +648,10 @@ void DiveListView::markDiveInvalid()
 		// d->invalid = true;
 	}
 	if (amount_selected == 0) {
-		mainWindow()->cleanUpEmpty();
+		MainWindow::instance()->cleanUpEmpty();
 	}
 	mark_divelist_changed(true);
-	mainWindow()->refreshDisplay();
+	MainWindow::instance()->refreshDisplay();
 	if (prefs.display_invalid_dives == false) {
 		clearSelection();
 		// select top dive that isn't marked invalid
@@ -679,10 +679,10 @@ void DiveListView::deleteDive()
 		lastDiveNr = i;
 	}
 	if (amount_selected == 0) {
-		mainWindow()->cleanUpEmpty();
+		MainWindow::instance()->cleanUpEmpty();
 	}
 	mark_divelist_changed(true);
-	mainWindow()->refreshDisplay();
+	MainWindow::instance()->refreshDisplay();
 	if (lastDiveNr != -1) {
 		clearSelection();
 		selectDive(lastDiveNr);
@@ -769,7 +769,7 @@ void DiveListView::saveSelectedDivesAs()
 	}
 	settings.endGroup();
 
-	QString fileName = QFileDialog::getSaveFileName(mainWindow(), tr("Save Dives As..."), QDir::homePath());
+	QString fileName = QFileDialog::getSaveFileName(MainWindow::instance(), tr("Save Dives As..."), QDir::homePath());
 	if (fileName.isEmpty())
 		return;
 
@@ -842,25 +842,25 @@ void DiveListView::loadImages()
 				if (dive->when > imagetime) {
 					;  // Before dive
 					add_event(&(dive->dc), 0, 123, 0, 0, fileNames.at(i).toUtf8().data());
-					mainWindow()->refreshDisplay();
+					MainWindow::instance()->refreshDisplay();
 					mark_divelist_changed(true);
 				}
 				else if (dive->when + dive->duration.seconds < imagetime){
 					;  // After dive
 					add_event(&(dive->dc), dive->duration.seconds, 123, 0, 0, fileNames.at(i).toUtf8().data());
-					mainWindow()->refreshDisplay();
+					MainWindow::instance()->refreshDisplay();
 					mark_divelist_changed(true);
 				}
 				else {
 					add_event(&(dive->dc), imagetime - dive->when, 123, 0, 0, fileNames.at(i).toUtf8().data());
-					mainWindow()->refreshDisplay();
+					MainWindow::instance()->refreshDisplay();
 					mark_divelist_changed(true);
 				}
 				if (!dive->latitude.udeg && !IS_FP_SAME(exif.GeoLocation.Latitude, 0.0)){
 					dive->latitude.udeg = lrint(1000000.0 * exif.GeoLocation.Latitude);
 					dive->longitude.udeg = lrint(1000000.0 * exif.GeoLocation.Longitude);
 					mark_divelist_changed(true);
-					mainWindow()->refreshDisplay();
+					MainWindow::instance()->refreshDisplay();
 				}
 			}
 		}
diff --git a/qt-ui/divelogimportdialog.cpp b/qt-ui/divelogimportdialog.cpp
index 0a513de62..3005d1584 100644
--- a/qt-ui/divelogimportdialog.cpp
+++ b/qt-ui/divelogimportdialog.cpp
@@ -68,7 +68,7 @@ void DiveLogImportDialog::on_buttonBox_accepted()
 			               specialCSV.contains(ui->knownImports->currentIndex()) ? CSVApps[ui->knownImports->currentIndex()].name.toUtf8().data() : "csv",
 			               &error);
 			if (error != NULL) {
-				mainWindow()->showError(error);
+				MainWindow::instance()->showError(error);
 				free(error);
 				error = NULL;
 			}
@@ -87,7 +87,7 @@ void DiveLogImportDialog::on_buttonBox_accepted()
 			               VALUE_IF_CHECKED(Tags),
 			               &error);
 			if (error != NULL) {
-				mainWindow()->showError(error);
+				MainWindow::instance()->showError(error);
 				free(error);
 				error = NULL;
 			}
@@ -95,7 +95,7 @@ void DiveLogImportDialog::on_buttonBox_accepted()
 	}
 	process_dives(true, false);
 
-	mainWindow()->refreshDisplay();
+	MainWindow::instance()->refreshDisplay();
 }
 
 #define SET_VALUE_AND_CHECKBOX(CSV, BOX, VAL) ({\
diff --git a/qt-ui/diveplanner.cpp b/qt-ui/diveplanner.cpp
index 2a70b8d93..225c05569 100644
--- a/qt-ui/diveplanner.cpp
+++ b/qt-ui/diveplanner.cpp
@@ -371,7 +371,7 @@ void DivePlannerGraphics::decreaseDepth()
 
 	Q_FOREACH(DiveHandler *d, handles) {
 		if (depthLine->valueAt(d->pos()) > depthLine->maximum() - M_OR_FT(10,30)) {
-			QMessageBox::warning(mainWindow(),
+			QMessageBox::warning(MainWindow::instance(),
 				tr("Handler Position Error"),
 				tr("One or more of your stops will be lost with this operations, \n"
 					"Please, remove them first."));
@@ -979,9 +979,9 @@ DivePlannerWidget::DivePlannerWidget(QWidget* parent, Qt::WindowFlags f): QWidge
 	// Creating the plan
 	connect(ui.buttonBox, SIGNAL(accepted()), plannerModel, SLOT(createPlan()));
 	connect(ui.buttonBox, SIGNAL(rejected()), plannerModel, SLOT(cancelPlan()));
-	connect(plannerModel, SIGNAL(planCreated()), mainWindow(), SLOT(showProfile()));
-	connect(plannerModel, SIGNAL(planCreated()), mainWindow(), SLOT(refreshDisplay()));
-	connect(plannerModel, SIGNAL(planCanceled()), mainWindow(), SLOT(showProfile()));
+	connect(plannerModel, SIGNAL(planCreated()), MainWindow::instance(), SLOT(showProfile()));
+	connect(plannerModel, SIGNAL(planCreated()), MainWindow::instance(), SLOT(refreshDisplay()));
+	connect(plannerModel, SIGNAL(planCanceled()), MainWindow::instance(), SLOT(showProfile()));
 
 	/* set defaults. */
 	ui.startTime->setTime( QTime(1, 0) );
@@ -1298,7 +1298,7 @@ struct diveplan DivePlannerPointsModel::getDiveplan()
 void DivePlannerPointsModel::cancelPlan()
 {
 	if (mode == PLAN && rowCount()) {
-		if (QMessageBox::warning(mainWindow(), TITLE_OR_TEXT(tr("Discard the Plan?"),
+		if (QMessageBox::warning(MainWindow::instance(), TITLE_OR_TEXT(tr("Discard the Plan?"),
 			tr("You are about to discard your plan.")),
 			QMessageBox::Discard | QMessageBox::Cancel, QMessageBox::Discard) != QMessageBox::Discard) {
 			return;
diff --git a/qt-ui/downloadfromdivecomputer.cpp b/qt-ui/downloadfromdivecomputer.cpp
index d32112224..5dc38ca0a 100644
--- a/qt-ui/downloadfromdivecomputer.cpp
+++ b/qt-ui/downloadfromdivecomputer.cpp
@@ -269,7 +269,7 @@ void DownloadFromDCWidget::on_ok_clicked()
 	connect(thread, SIGNAL(finished()),
 			this, SLOT(onDownloadThreadFinished()), Qt::QueuedConnection);
 
-	MainWindow *w = mainWindow();
+	MainWindow *w = MainWindow::instance();
 	connect(thread, SIGNAL(finished()), w, SLOT(refreshDisplay()));
 
 	// before we start, remember where the dive_table ended
diff --git a/qt-ui/globe.cpp b/qt-ui/globe.cpp
index b3dcc0485..240f8d904 100644
--- a/qt-ui/globe.cpp
+++ b/qt-ui/globe.cpp
@@ -108,7 +108,7 @@ void GlobeGPS::contextMenuEvent(QContextMenuEvent* ev)
 void GlobeGPS::mouseClicked(qreal lon, qreal lat, GeoDataCoordinates::Unit unit)
 {
 	// don't mess with the selection while the user is editing a dive
-	if (mainWindow()->information()->isEditing())
+	if (MainWindow::instance()->information()->isEditing())
 		return;
 
 	GeoDataCoordinates here(lon, lat, unit);
@@ -151,10 +151,10 @@ void GlobeGPS::mouseClicked(qreal lon, qreal lat, GeoDataCoordinates::Unit unit)
 	if (selectedDiveIds.empty())
 		return;
 	if (clear) {
-		mainWindow()->dive_list()->unselectDives();
+		MainWindow::instance()->dive_list()->unselectDives();
 		clear = false;
 	}
-	mainWindow()->dive_list()->selectDives(selectedDiveIds);
+	MainWindow::instance()->dive_list()->selectDives(selectedDiveIds);
 }
 
 void GlobeGPS::repopulateLabels()
@@ -210,7 +210,7 @@ void GlobeGPS::centerOn(dive* dive)
 	qreal longitude = dive->longitude.udeg / 1000000.0;
 	qreal latitude = dive->latitude.udeg / 1000000.0;
 
-	if (!longitude || !latitude || mainWindow()->information()->isEditing()) {
+	if (!longitude || !latitude || MainWindow::instance()->information()->isEditing()) {
 		prepareForGetDiveCoordinates();
 		return;
 	}
@@ -249,7 +249,7 @@ void GlobeGPS::changeDiveGeoPosition(qreal lon, qreal lat, GeoDataCoordinates::U
 {
 	messageWidget->hide();
 
-	if (mainWindow()->dive_list()->selectionModel()->selection().isEmpty())
+	if (MainWindow::instance()->dive_list()->selectionModel()->selection().isEmpty())
 		return;
 
 	// convert to degrees if in radian.
@@ -270,7 +270,7 @@ void GlobeGPS::changeDiveGeoPosition(qreal lon, qreal lat, GeoDataCoordinates::U
 	centerOn(lon, lat, true);
 	editingDiveLocation = false;
 	mark_divelist_changed(true);
-	mainWindow()->refreshDisplay();
+	MainWindow::instance()->refreshDisplay();
 }
 
 void GlobeGPS::mousePressEvent(QMouseEvent* event)
@@ -279,8 +279,8 @@ void GlobeGPS::mousePressEvent(QMouseEvent* event)
 	bool clickOnGlobe = geoCoordinates(event->pos().x(), event->pos().y(), lon, lat, GeoDataCoordinates::Degree);
 
 	// there could be two scenarios that got us here; let's check if we are editing a dive
-	if (mainWindow()->information()->isEditing() && clickOnGlobe) {
-		mainWindow()->information()->updateCoordinatesText(lat, lon);
+	if (MainWindow::instance()->information()->isEditing() && clickOnGlobe) {
+		MainWindow::instance()->information()->updateCoordinatesText(lat, lon);
 		repopulateLabels();
 	} else if (clickOnGlobe) {
 		changeDiveGeoPosition(lon, lat, GeoDataCoordinates::Degree);
diff --git a/qt-ui/maintab.cpp b/qt-ui/maintab.cpp
index b65d572fd..d878a68e9 100644
--- a/qt-ui/maintab.cpp
+++ b/qt-ui/maintab.cpp
@@ -234,14 +234,14 @@ void MainTab::enableEdition(EditMode newEditMode)
 	    strcmp(current_dive->dc.model, "manually added dive") == 0) {
 		// editCurrentDive will call enableEdition with newEditMode == MANUALLY_ADDED_DIVE
 		// so exit this function here after editCurrentDive() returns
-		mainWindow()->editCurrentDive();
+		MainWindow::instance()->editCurrentDive();
 		return;
 	}
-	mainWindow()->dive_list()->setEnabled(false);
-	mainWindow()->globe()->prepareForGetDiveCoordinates();
+	MainWindow::instance()->dive_list()->setEnabled(false);
+	MainWindow::instance()->globe()->prepareForGetDiveCoordinates();
 	// We may be editing one or more dives here. backup everything.
 	notesBackup.clear();
-	if (mainWindow() && mainWindow()->dive_list()->selectedTrips().count() == 1) {
+	if (MainWindow::instance() && MainWindow::instance()->dive_list()->selectedTrips().count() == 1) {
 		// we are editing trip location and notes
 		displayMessage(tr("This trip is being edited."));
 		notesBackup[NULL].notes = ui.notes->toPlainText();
@@ -399,7 +399,7 @@ void MainTab::updateDiveInfo(int dive)
 	if (d) {
 		updateGpsCoordinates(d);
 		ui.dateTimeEdit->setDateTime(QDateTime::fromTime_t(d->when).toUTC());
-		if (mainWindow() && mainWindow()->dive_list()->selectedTrips().count() == 1) {
+		if (MainWindow::instance() && MainWindow::instance()->dive_list()->selectedTrips().count() == 1) {
 			setTabText(0, tr("Trip Notes"));
 			// only use trip relevant fields
 			ui.coordinates->setVisible(false);
@@ -421,7 +421,7 @@ void MainTab::updateDiveInfo(int dive)
 			ui.waterTempLabel->setVisible(false);
 			ui.watertemp->setVisible(false);
 			// rename the remaining fields and fill data from selected trip
-			dive_trip_t *currentTrip = *mainWindow()->dive_list()->selectedTrips().begin();
+			dive_trip_t *currentTrip = *MainWindow::instance()->dive_list()->selectedTrips().begin();
 			ui.LocationLabel->setText(tr("Trip Location"));
 			ui.location->setText(currentTrip->location);
 			ui.NotesLabel->setText(tr("Trip Notes"));
@@ -572,13 +572,13 @@ void MainTab::reload()
 
 void MainTab::acceptChanges()
 {
-	mainWindow()->dive_list()->setEnabled(true);
+	MainWindow::instance()->dive_list()->setEnabled(true);
 	tabBar()->setTabIcon(0, QIcon()); // Notes
 	tabBar()->setTabIcon(1, QIcon()); // Equipment
 	hideMessage();
 	ui.equipmentTab->setEnabled(true);
 	/* now figure out if things have changed */
-	if (mainWindow() && mainWindow()->dive_list()->selectedTrips().count() == 1) {
+	if (MainWindow::instance() && MainWindow::instance()->dive_list()->selectedTrips().count() == 1) {
 		if (notesBackup[NULL].notes != ui.notes->toPlainText() ||
 			notesBackup[NULL].location != ui.location->text())
 			mark_divelist_changed(true);
@@ -602,7 +602,7 @@ void MainTab::acceptChanges()
 		}
 		if (notesBackup[curr].location != ui.location->text() ||
 			notesBackup[curr].coordinates != ui.coordinates->text()) {
-			mainWindow()->globe()->reload();
+			MainWindow::instance()->globe()->reload();
 		}
 
 		if (notesBackup[curr].tags != ui.tagWidget->text())
@@ -644,7 +644,7 @@ void MainTab::acceptChanges()
 		else if (selected_dive == dive_table.nr - 1 && get_dive(dive_table.nr - 2)->number)
 			current_dive->number = get_dive(dive_table.nr - 2)->number + 1;
 		DivePlannerPointsModel::instance()->cancelPlan();
-		mainWindow()->showProfile();
+		MainWindow::instance()->showProfile();
 		mark_divelist_changed(true);
 		DivePlannerPointsModel::instance()->setPlanMode(DivePlannerPointsModel::NOTHING);
 	}
@@ -654,10 +654,10 @@ void MainTab::acceptChanges()
 		if (d)
 			fixup_dive(d);
 	}
-	int scrolledBy = mainWindow()->dive_list()->verticalScrollBar()->sliderPosition();
+	int scrolledBy = MainWindow::instance()->dive_list()->verticalScrollBar()->sliderPosition();
 	resetPallete();
 	if (editMode == ADD || editMode == MANUALLY_ADDED_DIVE) {
-		mainWindow()->dive_list()->unselectDives();
+		MainWindow::instance()->dive_list()->unselectDives();
 		struct dive *d = get_dive(dive_table.nr -1 );
 		// mark the dive as remembered (abusing the selected flag)
 		// and then clear that flag out on the other side of the sort_table()
@@ -671,17 +671,17 @@ void MainTab::acceptChanges()
 			}
 		}
 		editMode = NONE;
-		mainWindow()->refreshDisplay();
-		mainWindow()->dive_list()->selectDive( i, true );
+		MainWindow::instance()->refreshDisplay();
+		MainWindow::instance()->dive_list()->selectDive( i, true );
 	} else {
 		editMode = NONE;
-		mainWindow()->dive_list()->rememberSelection();
+		MainWindow::instance()->dive_list()->rememberSelection();
 		sort_table(&dive_table);
-		mainWindow()->refreshDisplay();
-		mainWindow()->dive_list()->restoreSelection();
+		MainWindow::instance()->refreshDisplay();
+		MainWindow::instance()->dive_list()->restoreSelection();
 	}
-	mainWindow()->dive_list()->verticalScrollBar()->setSliderPosition(scrolledBy);
-	mainWindow()->dive_list()->setFocus();
+	MainWindow::instance()->dive_list()->verticalScrollBar()->setSliderPosition(scrolledBy);
+	MainWindow::instance()->dive_list()->setFocus();
 }
 
 void MainTab::resetPallete()
@@ -715,8 +715,8 @@ void MainTab::rejectChanges()
 	tabBar()->setTabIcon(0, QIcon()); // Notes
 	tabBar()->setTabIcon(1, QIcon()); // Equipment
 
-	mainWindow()->dive_list()->setEnabled(true);
-	if (mainWindow() && mainWindow()->dive_list()->selectedTrips().count() == 1) {
+	MainWindow::instance()->dive_list()->setEnabled(true);
+	if (MainWindow::instance() && MainWindow::instance()->dive_list()->selectedTrips().count() == 1) {
 		ui.notes->setText(notesBackup[NULL].notes );
 		ui.location->setText(notesBackup[NULL].location);
 	} else {
@@ -777,8 +777,8 @@ void MainTab::rejectChanges()
 		updateGpsCoordinates(curr);
 		if (lastMode == ADD) {
 			delete_single_dive(selected_dive);
-			mainWindow()->dive_list()->reload(DiveTripModel::CURRENT);
-			mainWindow()->dive_list()->restoreSelection();
+			MainWindow::instance()->dive_list()->reload(DiveTripModel::CURRENT);
+			MainWindow::instance()->dive_list()->restoreSelection();
 		}
 		if (selected_dive >= 0) {
 			multiEditEquipmentPlaceholder = *get_dive(selected_dive);
@@ -792,20 +792,20 @@ void MainTab::rejectChanges()
 	}
 
 	hideMessage();
-	mainWindow()->dive_list()->setEnabled(true);
+	MainWindow::instance()->dive_list()->setEnabled(true);
 	notesBackup.clear();
 	resetPallete();
 	editMode = NONE;
-	mainWindow()->globe()->reload();
+	MainWindow::instance()->globe()->reload();
 	if (lastMode == ADD || lastMode == MANUALLY_ADDED_DIVE) {
 		// more clean up
 		updateDiveInfo(selected_dive);
-		mainWindow()->showProfile();
+		MainWindow::instance()->showProfile();
 		// we already reloaded the divelist above, so don't recreate it or we'll lose the selection
-		mainWindow()->refreshDisplay(false);
+		MainWindow::instance()->refreshDisplay(false);
 		DivePlannerPointsModel::instance()->setPlanMode(DivePlannerPointsModel::NOTHING);
 	}
-	mainWindow()->dive_list()->setFocus();
+	MainWindow::instance()->dive_list()->setFocus();
 }
 #undef EDIT_TEXT2
 
@@ -888,9 +888,9 @@ void MainTab::on_location_textChanged(const QString& text)
 {
 	if (editMode == NONE)
 		return;
-	if (editMode == TRIP && mainWindow() && mainWindow()->dive_list()->selectedTrips().count() == 1) {
+	if (editMode == TRIP && MainWindow::instance() && MainWindow::instance()->dive_list()->selectedTrips().count() == 1) {
 		// we are editing a trip
-		dive_trip_t *currentTrip = *mainWindow()->dive_list()->selectedTrips().begin();
+		dive_trip_t *currentTrip = *MainWindow::instance()->dive_list()->selectedTrips().begin();
 		EDIT_TEXT(currentTrip->location, text);
 	} else if (editMode == DIVE || editMode == ADD || editMode == MANUALLY_ADDED_DIVE) {
 		if (!ui.coordinates->isModified() ||
@@ -911,7 +911,7 @@ void MainTab::on_location_textChanged(const QString& text)
 			}
 		}
 		EDIT_SELECTED_DIVES( EDIT_TEXT(mydive->location, text) );
-		mainWindow()->globe()->repopulateLabels();
+		MainWindow::instance()->globe()->repopulateLabels();
 	}
 	markChangedWidget(ui.location);
 }
@@ -926,9 +926,9 @@ void MainTab::on_notes_textChanged()
 {
 	if (editMode == NONE)
 		return;
-	if (editMode == TRIP && mainWindow() && mainWindow()->dive_list()->selectedTrips().count() == 1) {
+	if (editMode == TRIP && MainWindow::instance() && MainWindow::instance()->dive_list()->selectedTrips().count() == 1) {
 		// we are editing a trip
-		dive_trip_t *currentTrip = *mainWindow()->dive_list()->selectedTrips().begin();
+		dive_trip_t *currentTrip = *MainWindow::instance()->dive_list()->selectedTrips().begin();
 		EDIT_TEXT(currentTrip->notes, ui.notes->toPlainText());
 	} else if (editMode == DIVE || editMode == ADD || editMode == MANUALLY_ADDED_DIVE) {
 		EDIT_SELECTED_DIVES( EDIT_TEXT(mydive->notes, ui.notes->toPlainText()) );
diff --git a/qt-ui/mainwindow.cpp b/qt-ui/mainwindow.cpp
index 217c66dbb..8795b93df 100644
--- a/qt-ui/mainwindow.cpp
+++ b/qt-ui/mainwindow.cpp
@@ -36,12 +36,7 @@
 #include "printdialog.h"
 #include "divelogimportdialog.h"
 
-static MainWindow* instance = 0;
-
-MainWindow* mainWindow()
-{
-	return instance;
-}
+MainWindow *MainWindow::m_Instance = NULL;
 
 MainWindow::MainWindow() : QMainWindow(),
 	actionNextDive(0),
@@ -49,7 +44,7 @@ MainWindow::MainWindow() : QMainWindow(),
 	helpView(0),
 	state(VIEWALL)
 {
-	instance = this;
+	m_Instance = this;
 	ui.setupUi(this);
 	setWindowIcon(QIcon(":subsurface-icon"));
 	connect(ui.ListWidget, SIGNAL(currentDiveChanged(int)), this, SLOT(current_dive_changed(int)));
@@ -79,6 +74,16 @@ MainWindow::MainWindow() : QMainWindow(),
 #endif
 }
 
+MainWindow::~MainWindow()
+{
+	m_Instance = NULL;
+}
+
+MainWindow *MainWindow::instance()
+{
+	return m_Instance;
+}
+
 // this gets called after we download dives from a divecomputer
 void MainWindow::refreshDisplay(bool recreateDiveList)
 {
diff --git a/qt-ui/mainwindow.h b/qt-ui/mainwindow.h
index a1b678296..deacdec76 100644
--- a/qt-ui/mainwindow.h
+++ b/qt-ui/mainwindow.h
@@ -41,6 +41,8 @@ public:
 	enum CurrentState{ VIEWALL, GLOBE_MAXIMIZED, INFO_MAXIMIZED, PROFILE_MAXIMIZED, LIST_MAXIMIZED};
 
 	MainWindow();
+	virtual ~MainWindow();
+	static MainWindow *instance();
 	ProfileGraphicsView *graphics();
 	MainTab *information();
 	DiveListView *dive_list();
@@ -135,6 +137,7 @@ private:
 	UserManual *helpView;
 	CurrentState state;
 	QString filter();
+	static MainWindow *m_Instance;
 	bool askSaveChanges();
 	void writeSettings();
 	void redrawProfile();
diff --git a/qt-ui/models.cpp b/qt-ui/models.cpp
index 942be2e5a..66a79fc90 100644
--- a/qt-ui/models.cpp
+++ b/qt-ui/models.cpp
@@ -334,7 +334,7 @@ void CylindersModel::remove(const QModelIndex& index)
 	}
 	cylinder_t *cyl = &current->cylinder[index.row()];
 	if (DivePlannerPointsModel::instance()->tankInUse(cyl->gasmix.o2.permille, cyl->gasmix.he.permille)) {
-		QMessageBox::warning(mainWindow(), TITLE_OR_TEXT(
+		QMessageBox::warning(MainWindow::instance(), TITLE_OR_TEXT(
 				tr("Cylinder cannot be removed"),
 				tr("This gas in use. Only cylinders that are not used in the dive can be removed.")),
 				QMessageBox::Ok);
diff --git a/qt-ui/preferences.cpp b/qt-ui/preferences.cpp
index f3a88fcd3..01f1815c2 100644
--- a/qt-ui/preferences.cpp
+++ b/qt-ui/preferences.cpp
@@ -8,7 +8,7 @@
 
 PreferencesDialog* PreferencesDialog::instance()
 {
-	static PreferencesDialog *dialog = new PreferencesDialog(mainWindow());
+	static PreferencesDialog *dialog = new PreferencesDialog(MainWindow::instance());
 	dialog->setAttribute(Qt::WA_QuitOnClose, false);
 	LanguageModel::instance();
 	return dialog;
@@ -209,7 +209,7 @@ void PreferencesDialog::syncSettings()
 	bool useSystemLang = s.value("UseSystemLanguage", true).toBool();
 	if (useSystemLang != ui.languageSystemDefault->isChecked() ||
 	    (!useSystemLang && s.value("UiLanguage").toString() != ui.languageView->currentIndex().data(Qt::UserRole))) {
-		QMessageBox::warning(mainWindow(), tr("Restart required"),
+		QMessageBox::warning(MainWindow::instance(), tr("Restart required"),
 				     tr("To correctly load a new language you must restart Subsurface."));
 	}
 	s.setValue("UseSystemLanguage", ui.languageSystemDefault->isChecked());
diff --git a/qt-ui/printlayout.cpp b/qt-ui/printlayout.cpp
index c76068769..ec30b8369 100644
--- a/qt-ui/printlayout.cpp
+++ b/qt-ui/printlayout.cpp
@@ -131,7 +131,7 @@ void PrintLayout::printProfileDives(int divesPerRow, int divesPerColumn)
 	painter.scale(scaleX, scaleY);
 
 	// setup the profile widget
-	ProfileGraphicsView *profile = mainWindow()->graphics();
+	ProfileGraphicsView *profile = MainWindow::instance()->graphics();
 	const int profileFrameStyle = profile->frameStyle();
 	profile->setFrameStyle(QFrame::NoFrame);
 	profile->clear();
diff --git a/qt-ui/profile/profilewidget2.cpp b/qt-ui/profile/profilewidget2.cpp
index cfe8e7f82..788c2808e 100644
--- a/qt-ui/profile/profilewidget2.cpp
+++ b/qt-ui/profile/profilewidget2.cpp
@@ -88,7 +88,7 @@ ProfileWidget2::ProfileWidget2(QWidget *parent) :
 #ifndef QT_NO_DEBUG
 	QTableView *diveDepthTableView = new QTableView();
 	diveDepthTableView->setModel(dataModel);
-	mainWindow()->tabWidget()->addTab(diveDepthTableView, "Depth Model");
+	MainWindow::instance()->tabWidget()->addTab(diveDepthTableView, "Depth Model");
 #endif
 }
 
diff --git a/qt-ui/profilegraphics.cpp b/qt-ui/profilegraphics.cpp
index 14df03eb1..6ae765d7a 100644
--- a/qt-ui/profilegraphics.cpp
+++ b/qt-ui/profilegraphics.cpp
@@ -196,7 +196,7 @@ void ProfileGraphicsView::changeGas()
 	add_gas_switch_event(current_dive, current_dc, seconds, get_gasidx(current_dive, o2, he));
 	// this means we potentially have a new tank that is being used and needs to be shown
 	fixup_dive(current_dive);
-	mainWindow()->information()->updateDiveInfo(selected_dive);
+	MainWindow::instance()->information()->updateDiveInfo(selected_dive);
 	mark_divelist_changed(true);
 	plot(current_dive, true);
 }
@@ -207,7 +207,7 @@ void ProfileGraphicsView::hideEvents()
 	EventItem *item = static_cast<EventItem*>(action->data().value<void*>());
 	struct event *event = item->ev;
 
-	if (QMessageBox::question(mainWindow(), TITLE_OR_TEXT(
+	if (QMessageBox::question(MainWindow::instance(), TITLE_OR_TEXT(
 				  tr("Hide events"),
 				  tr("Hide all %1 events?").arg(event->name)),
 				  QMessageBox::Ok | QMessageBox::Cancel) == QMessageBox::Ok) {
@@ -237,7 +237,7 @@ void ProfileGraphicsView::removeEvent()
 	EventItem *item = static_cast<EventItem*>(action->data().value<void*>());
 	struct event *event = item->ev;
 
-	if (QMessageBox::question(mainWindow(), TITLE_OR_TEXT(
+	if (QMessageBox::question(MainWindow::instance(), TITLE_OR_TEXT(
 				  tr("Remove the selected event?"),
 				  tr("%1 @ %2:%3").arg(event->name)
 				  .arg(event->time.seconds / 60)
@@ -375,13 +375,13 @@ void ProfileGraphicsView::plot(struct dive *d, bool forceRedraw)
 	diveId = d ? d->id : 0;
 	diveDC = d ? dc : NULL;
 
-	if (!isVisible() || !d || !mainWindow()) {
+	if (!isVisible() || !d || !MainWindow::instance()) {
 		return;
 	}
 	setBackgroundBrush(getColor(BACKGROUND));
 
 	// best place to put the focus stealer code.
-	setFocusProxy(mainWindow()->dive_list());
+	setFocusProxy(MainWindow::instance()->dive_list());
 	scene()->setSceneRect(0,0, viewport()->width()-50, viewport()->height()-50);
 
 	toolTip = new ToolTipItem();
@@ -546,7 +546,7 @@ void ProfileGraphicsView::addControlItems(struct dive *d)
 	if (defaultDC == "manually added dive" || defaultDC == "planned dive") {
 		QAction *editAction = new QAction(QIcon(":edit"), tr("Edit"), this);
 		toolBar->addAction(editAction);
-		connect(editAction, SIGNAL(triggered()), mainWindow(), SLOT(editCurrentDive()));
+		connect(editAction, SIGNAL(triggered()), MainWindow::instance(), SLOT(editCurrentDive()));
 	}
 	toolBarProxy = scene()->addWidget(toolBar);
 	toolBarProxy->setPos(mapToScene(TOOLBAR_POS));
@@ -1628,7 +1628,7 @@ GraphicsTextEditor::GraphicsTextEditor(QGraphicsItem* parent): QGraphicsTextItem
 void GraphicsTextEditor::mouseDoubleClickEvent(QGraphicsSceneMouseEvent* event)
 {
 	// Remove the proxy filter so we can focus here.
-	mainWindow()->graphics()->setFocusProxy(0);
+	MainWindow::instance()->graphics()->setFocusProxy(0);
 	setTextInteractionFlags(Qt::TextEditorInteraction | Qt::TextEditable);
 }
 
@@ -1637,7 +1637,7 @@ void GraphicsTextEditor::keyReleaseEvent(QKeyEvent* event)
 	if (event->key() == Qt::Key_Enter || event->key() == Qt::Key_Return) {
 		setTextInteractionFlags(Qt::NoTextInteraction);
 		emit editingFinished( toPlainText() );
-		mainWindow()->graphics()->setFocusProxy(mainWindow()->dive_list());
+		MainWindow::instance()->graphics()->setFocusProxy(MainWindow::instance()->dive_list());
 		return;
 	}
 	emit textChanged( toPlainText() );
diff --git a/qt-ui/simplewidgets.cpp b/qt-ui/simplewidgets.cpp
index d69425ef9..2a0b48307 100644
--- a/qt-ui/simplewidgets.cpp
+++ b/qt-ui/simplewidgets.cpp
@@ -107,7 +107,7 @@ void MinMaxAvgWidget::setMinimum(const QString& minimum)
 
 RenumberDialog* RenumberDialog::instance()
 {
-	static RenumberDialog* self = new RenumberDialog(mainWindow());
+	static RenumberDialog* self = new RenumberDialog(MainWindow::instance());
 	return self;
 }
 
@@ -127,7 +127,7 @@ RenumberDialog::RenumberDialog(QWidget *parent): QDialog(parent)
 
 ShiftTimesDialog* ShiftTimesDialog::instance()
 {
-	static ShiftTimesDialog* self = new ShiftTimesDialog(mainWindow());
+	static ShiftTimesDialog* self = new ShiftTimesDialog(MainWindow::instance());
 	return self;
 }
 
@@ -144,9 +144,9 @@ void ShiftTimesDialog::buttonClicked(QAbstractButton* button)
 			shift_times(amount);
 			sort_table(&dive_table);
 			mark_divelist_changed(true);
-			mainWindow()->dive_list()->rememberSelection();
-			mainWindow()->refreshDisplay();
-			mainWindow()->dive_list()->restoreSelection();
+			MainWindow::instance()->dive_list()->rememberSelection();
+			MainWindow::instance()->refreshDisplay();
+			MainWindow::instance()->dive_list()->restoreSelection();
 		}
 	}
 }
diff --git a/qt-ui/subsurfacewebservices.cpp b/qt-ui/subsurfacewebservices.cpp
index 918cf53f3..86dbf5015 100644
--- a/qt-ui/subsurfacewebservices.cpp
+++ b/qt-ui/subsurfacewebservices.cpp
@@ -333,9 +333,9 @@ void SubsurfaceWebServices::buttonClicked(QAbstractButton* button)
 		/* now merge the data in the gps_location table into the dive_table */
 		if (merge_locations_into_dives()) {
 			mark_divelist_changed(true);
-			mainWindow()->globe()->repopulateLabels();
-			mainWindow()->globe()->centerOn(current_dive);
-			mainWindow()->information()->updateDiveInfo(selected_dive);
+			MainWindow::instance()->globe()->repopulateLabels();
+			MainWindow::instance()->globe()->centerOn(current_dive);
+			MainWindow::instance()->information()->updateDiveInfo(selected_dive);
 		}
 
 		/* store last entered uid in config */
@@ -558,7 +558,7 @@ out:
 
 DivelogsDeWebServices* DivelogsDeWebServices::instance()
 {
-	static DivelogsDeWebServices *self = new DivelogsDeWebServices(mainWindow());
+	static DivelogsDeWebServices *self = new DivelogsDeWebServices(MainWindow::instance());
 	self->setAttribute(Qt::WA_QuitOnClose, false);
 	return self;
 }
@@ -586,7 +586,7 @@ void DivelogsDeWebServices::prepareDivesForUpload()
 			return;
 		}
 	}
-	mainWindow()->showError(errorText);
+	MainWindow::instance()->showError(errorText);
 }
 
 void DivelogsDeWebServices::uploadDives(QIODevice *dldContent)
@@ -855,11 +855,11 @@ void DivelogsDeWebServices::buttonClicked(QAbstractButton* button)
 		char *error = NULL;
 		parse_file(QFile::encodeName(zipFile.fileName()), &error);
 		if (error != NULL) {
-			mainWindow()->showError(error);
+			MainWindow::instance()->showError(error);
 			free(error);
 		}
 		process_dives(true, false);
-		mainWindow()->refreshDisplay();
+		MainWindow::instance()->refreshDisplay();
 
 		/* store last entered user/pass in config */
 		QSettings s;
diff --git a/qthelper.cpp b/qthelper.cpp
index acdb7c2ee..6f15517d4 100644
--- a/qthelper.cpp
+++ b/qthelper.cpp
@@ -6,7 +6,7 @@
 #include <QFileDialog>
 #include <QDebug>
 
-#define tr(_arg) mainWindow()->information()->tr(_arg)
+#define tr(_arg) MainWindow::instance()->information()->tr(_arg)
 DiveComputerList::DiveComputerList()
 {