Bug 549771: [SourceEditor] Fix widget is disposed exception when
R content assist is canceled

Change-Id: I05bcf9b12dc42445abc8e0534881adc01043a931
diff --git a/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpInfoHoverCreator.java b/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpInfoHoverCreator.java
index 545c773..bd793f4 100644
--- a/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpInfoHoverCreator.java
+++ b/r/org.eclipse.statet.r.ui/src/org/eclipse/statet/internal/r/ui/rhelp/RHelpInfoHoverCreator.java
@@ -526,7 +526,7 @@
 			this.hide= false;
 			updateInput();
 			waitCompleted();
-			if (this.hide) {
+			if (this.hide || !UIAccess.isOkToUse(getShell())) {
 				return;
 			}
 			
@@ -536,10 +536,7 @@
 			}
 			
 			if (Platform.WS_WIN32.equals(SWT.getPlatform())) {
-				final Shell shell= getShell();
-				if (shell != null) {
-					shell.moveAbove(null);
-				}
+				getShell().moveAbove(null);
 			}
 		}
 		else {