Limit monitor-specific scaling to supported autoscale modes

With these changes, Eclipse applications will not fail to start anymore
when an swt.autoScale value that is incompatible to monitor-specific
scaling on Windows is set.

The following changes are implemented:

- Upon starting an Eclipse application with an swt.autoScale setting that is not compatible with monitor-specific scaling on Windows, the monitor-specific scaling will be disabled and an error dialog will be shown
- Users won't be able to enable monitor-specific scaling from appearance page if unsupported swt.autoScale mode is set via system property / ini file

Author: ShahzaibIbrahim

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/Workbench.java

@@ -669,6 +669,13 @@ public void update() {
 				// run the legacy workbench once
 				returnCode[0] = workbench.runUI();
 
+				if (AUTOSCALE_ADAPTATION.isMonitorSpecificScalingDisabledForIncompatibility()) {
+					display.asyncExec(() -> {
+						MessageDialog.openError(null, WorkbenchMessages.RescaleAtRuntimeIncompatibilityTitle,
+								NLS.bind(WorkbenchMessages.RescaleAtRuntimeIncompatibilityDescription));
+					});
+				}
+
 				if (returnCode[0] == PlatformUI.RETURN_OK) {
 					// run the e4 event loop and instantiate ... well, stuff
 					if (serviceListener.get() != null) {
@@ -694,18 +701,6 @@ public void update() {
 		return returnCode[0];
 	}
 
-	private static void setRescaleAtRuntimePropertyFromPreference() {
-		if (System.getProperty(SWT_RESCALE_AT_RUNTIME_PROPERTY) != null) {
-			WorkbenchPlugin.log(Status.warning(SWT_RESCALE_AT_RUNTIME_PROPERTY
-					+ " is configured (e.g., via the INI), but the according preference should be preferred instead." //$NON-NLS-1$
-			));
-		} else {
-			boolean rescaleAtRuntime = ConfigurationScope.INSTANCE.getNode(WorkbenchPlugin.PI_WORKBENCH)
-					.getBoolean(IWorkbenchPreferenceConstants.RESCALING_AT_RUNTIME, true);
-			System.setProperty(SWT_RESCALE_AT_RUNTIME_PROPERTY, Boolean.toString(rescaleAtRuntime));
-		}
-	}
-
 	private static void setSearchContribution(MApplication app, boolean enabled) {
 		for (MTrimContribution contribution : app.getTrimContributions()) {
 			if ("org.eclipse.ui.ide.application.trimcontribution.QuickAccess".contains(contribution //$NON-NLS-1$
@@ -771,7 +766,7 @@ public static Display createDisplay() {
 			Display.setAppName(applicationName);
 		}
 
-		setRescaleAtRuntimePropertyFromPreference();
+		AUTOSCALE_ADAPTATION.setRescaleAtRuntimePropertyFromPreference();
 
 		// create the display
 		Display newDisplay = Display.getCurrent();
@@ -3673,6 +3668,8 @@ protected String createId() {
 	private static class AutoscaleAdaptation {
 		private static final String SWT_AUTOSCALE = "swt.autoScale"; //$NON-NLS-1$
 
+		private boolean incompatibleMonitorSpecificScalingDisabled;
+
 		private final String initialAutoScaleValue;
 
 		public AutoscaleAdaptation() {
@@ -3683,5 +3680,26 @@ public void runWithInitialAutoScaleValue(Runnable runnable) {
 			DPIUtil.runWithAutoScaleValue(initialAutoScaleValue, runnable);
 		}
 
+		public void setRescaleAtRuntimePropertyFromPreference() {
+			if (System.getProperty(SWT_RESCALE_AT_RUNTIME_PROPERTY) != null) {
+				WorkbenchPlugin.log(Status.warning(SWT_RESCALE_AT_RUNTIME_PROPERTY
+						+ " is configured (e.g., via the INI), but the according preference should be preferred instead." //$NON-NLS-1$
+				));
+			} else {
+				boolean rescaleAtRuntime = ConfigurationScope.INSTANCE.getNode(WorkbenchPlugin.PI_WORKBENCH)
+						.getBoolean(IWorkbenchPreferenceConstants.RESCALING_AT_RUNTIME, true);
+				System.setProperty(SWT_RESCALE_AT_RUNTIME_PROPERTY, Boolean.toString(rescaleAtRuntime));
+			}
+
+			if (DPIUtil.isMonitorSpecificScalingActive() && !DPIUtil.isSetupCompatibleToMonitorSpecificScaling()) {
+				incompatibleMonitorSpecificScalingDisabled = true;
+				System.setProperty(SWT_RESCALE_AT_RUNTIME_PROPERTY, Boolean.toString(false));
+			}
+		}
+
+		public boolean isMonitorSpecificScalingDisabledForIncompatibility() {
+			return incompatibleMonitorSpecificScalingDisabled;
+		}
+
 	}
 }

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/WorkbenchMessages.java

@@ -36,6 +36,12 @@ public class WorkbenchMessages extends NLS {
 
 	public static String RescaleAtRuntimeDescription;
 
+	public static String RescaleAtRuntimeDisabledDescription;
+
+	public static String RescaleAtRuntimeIncompatibilityTitle;
+
+	public static String RescaleAtRuntimeIncompatibilityDescription;
+
 	public static String RescaleAtRuntimeEnabled;
 
 	public static String RescaleAtRuntimeSettingChangeWarningTitle;

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/dialogs/ViewsPreferencePage.java

@@ -53,6 +53,7 @@
 import org.eclipse.jface.dialogs.MessageDialog;
 import org.eclipse.jface.fieldassist.ControlDecoration;
 import org.eclipse.jface.fieldassist.FieldDecorationRegistry;
+import org.eclipse.jface.layout.GridDataFactory;
 import org.eclipse.jface.preference.IPreferenceStore;
 import org.eclipse.jface.preference.PreferencePage;
 import org.eclipse.jface.viewers.ArrayContentProvider;
@@ -65,7 +66,9 @@
 import org.eclipse.swt.SWT;
 import org.eclipse.swt.events.SelectionEvent;
 import org.eclipse.swt.events.SelectionListener;
+import org.eclipse.swt.graphics.Font;
 import org.eclipse.swt.graphics.Image;
+import org.eclipse.swt.internal.DPIUtil;
 import org.eclipse.swt.layout.GridData;
 import org.eclipse.swt.layout.GridLayout;
 import org.eclipse.swt.widgets.Button;
@@ -222,7 +225,15 @@ private void createRescaleAtRuntimeCheckButton(Composite parent) {
 				.getBoolean(IWorkbenchPreferenceConstants.RESCALING_AT_RUNTIME, true);
 		rescaleAtRuntime = createCheckButton(parent, WorkbenchMessages.RescaleAtRuntimeEnabled,
 				initialStateRescaleAtRuntime);
-		rescaleAtRuntime.setToolTipText(WorkbenchMessages.RescaleAtRuntimeDescription);
+		if (!DPIUtil.isSetupCompatibleToMonitorSpecificScaling()) {
+			rescaleAtRuntime.setEnabled(false);
+			Font font = parent.getFont();
+			Composite note = createNoteComposite(font, parent, WorkbenchMessages.Preference_note,
+					WorkbenchMessages.RescaleAtRuntimeDisabledDescription);
+			note.setLayoutData(GridDataFactory.swtDefaults().span(2, 1).create());
+		} else {
+			rescaleAtRuntime.setToolTipText(WorkbenchMessages.RescaleAtRuntimeDescription);
+		}
 	}
 
 	private void createThemeIndependentComposits(Composite comp) {

bundles/org.eclipse.ui.workbench/eclipseui/org/eclipse/ui/internal/messages.properties

@@ -503,7 +503,10 @@ ThemeChangeWarningTitle = Theme Changed
 RescaleAtRuntimeSettingChangeWarningTitle = DPI Setting Changed
 RescaleAtRuntimeSettingChangeWarningText = Restart for the DPI setting changes to take effect
 RescaleAtRuntimeDescription = Activating this option will dynamically scale all windows according to the monitor they are currently in
+RescaleAtRuntimeDisabledDescription = Incompatible value for system property "swt.autoScale" is defined
 RescaleAtRuntimeEnabled = Use monitor-specific UI &scaling
+RescaleAtRuntimeIncompatibilityTitle = Monitor-Specific Scaling Deactivated
+RescaleAtRuntimeIncompatibilityDescription = Monitor-specific scaling is currently active but an incompatible "swt.autoScale" value is defined. For this reason, monitor-specific scaling has been disabled. Please review your auto-scaling configuration.
 # --- Workbench -----
 WorkbenchPreference_openMode=Open mode
 WorkbenchPreference_doubleClick=D&ouble click