Avoid access to default scope on read of configuration scope preference

The configuration scope preference for monitor-specific scaling is read
at a point in time where the workspace location may not have been
defined, so that the instance scope preferences cannot be accessed yet.
Since some defaults initializers require access to the instance scope,
the access to the configuration scope preference must avoid access to
the default scope in case no explicit value is set for that preference
yet.

This change adapts the access to the monitor-specific scaling
configuration scope preference to not access the default scope. Since
there may be further preference defaults initializers out of our control
that access instance scope preferences, just adapting those in the
Platform would not be a sufficient solution alternative.

Fixes #4085

Author: HeikoKlare

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

@@ -254,7 +254,6 @@
 import org.eclipse.ui.menus.IMenuService;
 import org.eclipse.ui.model.IContributionService;
 import org.eclipse.ui.operations.IWorkbenchOperationSupport;
-import org.eclipse.ui.preferences.ScopedPreferenceStore;
 import org.eclipse.ui.progress.IProgressService;
 import org.eclipse.ui.progress.WorkbenchJob;
 import org.eclipse.ui.services.IDisposable;
@@ -3748,8 +3747,8 @@ public void setRescaleAtRuntimePropertyFromPreference() {
 						+ " is configured (e.g., via the INI), but the according preference should be preferred instead." //$NON-NLS-1$
 				));
 			} else {
-				boolean rescaleAtRuntime = new ScopedPreferenceStore(ConfigurationScope.INSTANCE,
-						WorkbenchPlugin.PI_WORKBENCH).getBoolean(IWorkbenchPreferenceConstants.RESCALING_AT_RUNTIME);
+				boolean rescaleAtRuntime = ConfigurationScope.INSTANCE.getNode(WorkbenchPlugin.PI_WORKBENCH)
+						.getBoolean(IWorkbenchPreferenceConstants.RESCALING_AT_RUNTIME, true);
 				System.setProperty(SWT_RESCALE_AT_RUNTIME_PROPERTY, Boolean.toString(rescaleAtRuntime));
 			}