Bug 425928 - [Contributions] [regression] A toolbar command from CDT is
not visible in the Debug view toolbar in 4.4

Only consider creating the toolbar if the part itself has already been
instantiated.
diff --git a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/StackRenderer.java b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/StackRenderer.java
index 473076d..7baf907 100644
--- a/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/StackRenderer.java
+++ b/bundles/org.eclipse.e4.ui.workbench.renderers.swt/src/org/eclipse/e4/ui/workbench/renderers/swt/StackRenderer.java
@@ -765,7 +765,7 @@
 			}
 
 			ToolBar newViewTB = null;
-			if (needsTB) {
+			if (needsTB && part != null && part.getObject() != null) {
 				part.getToolbar().setVisible(true);
 				newViewTB = (ToolBar) renderer.createGui(part.getToolbar(),
 						ctf.getTopRight(), part.getContext());
diff --git a/tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/workbench/PartRenderingEngineTests.java b/tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/workbench/PartRenderingEngineTests.java
index 3834b36..ef47742 100644
--- a/tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/workbench/PartRenderingEngineTests.java
+++ b/tests/org.eclipse.e4.ui.tests/src/org/eclipse/e4/ui/tests/workbench/PartRenderingEngineTests.java
@@ -2171,6 +2171,8 @@
 		window.setSelectedElement(partStack);
 
 		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();
+		partA.setContributionURI("bundleclass://org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
+
 		partStack.getChildren().add(partA);
 		partStack.setSelectedElement(partA);
 
@@ -2178,6 +2180,8 @@
 		partA.setToolbar(toolBarA);
 
 		MPart partB = BasicFactoryImpl.eINSTANCE.createPart();
+		partB.setContributionURI("bundleclass://org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
+
 		partStack.getChildren().add(partB);
 
 		MToolBar toolBarB = MenuFactoryImpl.eINSTANCE.createToolBar();
@@ -2214,6 +2218,8 @@
 		application.setSelectedElement(window);
 
 		MPart part = BasicFactoryImpl.eINSTANCE.createPart();
+		part.setContributionURI("bundleclass://org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
+
 		window.getSharedElements().add(part);
 
 		MToolBar toolBar = MenuFactoryImpl.eINSTANCE.createToolBar();
@@ -2297,6 +2303,8 @@
 		window.setSelectedElement(partStack);
 
 		MPart partA = BasicFactoryImpl.eINSTANCE.createPart();
+		partA.setContributionURI("bundleclass://org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
+
 		partStack.getChildren().add(partA);
 		partStack.setSelectedElement(partA);
 
@@ -2304,6 +2312,8 @@
 		partA.setToolbar(toolBarA);
 
 		MPart partB = BasicFactoryImpl.eINSTANCE.createPart();
+		partB.setContributionURI("bundleclass://org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
+
 		partStack.getChildren().add(partB);
 
 		MToolBar toolBarB = MenuFactoryImpl.eINSTANCE.createToolBar();
@@ -2500,6 +2510,7 @@
 		application.setSelectedElement(window);
 
 		MPart part = BasicFactoryImpl.eINSTANCE.createPart();
+		part.setContributionURI("bundleclass://org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
 		window.getSharedElements().add(part);
 
 		MToolBar toolBar = MenuFactoryImpl.eINSTANCE.createToolBar();
@@ -2569,6 +2580,7 @@
 		application.setSelectedElement(window);
 
 		MPart part = BasicFactoryImpl.eINSTANCE.createPart();
+		part.setContributionURI("bundleclass://org.eclipse.e4.ui.tests/org.eclipse.e4.ui.tests.workbench.SampleView");
 		window.getSharedElements().add(part);
 
 		MToolBar toolBar = MenuFactoryImpl.eINSTANCE.createToolBar();