Guard shutdown dialog opener against workbench teardown

Review feedback: during postShutdown() the workbench may already be
gone, so reaching through PlatformUI via ProgressManagerUtil.safeToOpen
is unsafe. Scan display.getShells() for modal shells directly instead,
rename the scheduled runnable to openDialogLater to make the
schedule/cancel pairing obvious, and document the timerExec(-1, ...)
cancel call.

Author: vogella

bundles/org.eclipse.ui.ide.application/src/org/eclipse/ui/internal/ide/application/IDEWorkbenchAdvisor.java

@@ -61,6 +61,7 @@
 import org.eclipse.swt.graphics.Resource;
 import org.eclipse.swt.widgets.Display;
 import org.eclipse.swt.widgets.Listener;
+import org.eclipse.swt.widgets.Shell;
 import org.eclipse.ui.PlatformUI;
 import org.eclipse.ui.application.IWorkbenchConfigurer;
 import org.eclipse.ui.application.IWorkbenchWindowConfigurer;
@@ -79,7 +80,6 @@
 import org.eclipse.ui.internal.ide.IDEWorkbenchMessages;
 import org.eclipse.ui.internal.ide.IDEWorkbenchPlugin;
 import org.eclipse.ui.internal.ide.undo.WorkspaceUndoMonitor;
-import org.eclipse.ui.internal.progress.ProgressManagerUtil;
 import org.eclipse.ui.internal.progress.ProgressMonitorJobsDialog;
 import org.eclipse.ui.progress.IProgressService;
 import org.eclipse.ui.statushandlers.AbstractStatusHandler;
@@ -498,12 +498,12 @@ protected void disconnectFromWorkspace() {
 
 		final Display display = Display.getCurrent();
 		final int longOperationTime = savedLongOperationTime;
-		final Runnable openDialog = () -> {
-			if (ProgressManagerUtil.safeToOpen(dialog, null)) {
+		final Runnable openDialogLater = () -> {
+			if (!display.isDisposed() && !hasModalShell(display)) {
 				dialog.open();
 			}
 		};
-		display.timerExec(longOperationTime, openDialog);
+		display.timerExec(longOperationTime, openDialogLater);
 
 		try {
 			BusyIndicator.showWhile(display, () -> {
@@ -518,7 +518,8 @@ protected void disconnectFromWorkspace() {
 				}
 			});
 		} finally {
-			display.timerExec(-1, openDialog);
+			// Cancel openDialogLater if it is still pending; no-op if it already ran.
+			display.timerExec(-1, openDialogLater);
 		}
 
 		if (!status.isOK()) {
@@ -528,6 +529,16 @@ protected void disconnectFromWorkspace() {
 		}
 	}
 
+	private static boolean hasModalShell(Display display) {
+		final int modal = SWT.APPLICATION_MODAL | SWT.SYSTEM_MODAL | SWT.PRIMARY_MODAL;
+		for (Shell shell : display.getShells()) {
+			if (!shell.isDisposed() && shell.isVisible() && (shell.getStyle() & modal) != 0) {
+				return true;
+			}
+		}
+		return false;
+	}
+
 	@Override
 	public IAdaptable getDefaultPageInput() {
 		return ResourcesPlugin.getWorkspace().getRoot();