sfx2: fix race in JunitTest UndoManager.checkBrokenScripts()

1) checkBrokenScripts(complex.sfx2.UndoManager)
java.lang.NullPointerException
    at complex.sfx2.UndoManager.impl_clickButton(UndoManager.java:432)
    at complex.sfx2.UndoManager.checkBrokenScripts(UndoManager.java:188)

impl_clickButton() gets the wrong accessible object and throws.

The .uno:SwitchControlDesignMode is dispatched async, so make sure
it's processesed before trying to click the button.

See UnoControl::getAccessibleContext() "in design mode, use a fallback".

This was running in "rr record --chaos".

Change-Id: Iee9f25c2fff56d32e6b579b5d44ee6df9870fd8b

sfx2/qa/complex/sfx2/UndoManager.java

@@ -24,6 +24,7 @@ import com.sun.star.awt.Point;
 import com.sun.star.awt.Size;
 import com.sun.star.awt.XControl;
 import com.sun.star.awt.XControlModel;
+import com.sun.star.awt.XToolkitExperimental;
 import com.sun.star.beans.NamedValue;
 import com.sun.star.beans.XPropertySet;
 import com.sun.star.container.NoSuchElementException;
@@ -182,6 +183,10 @@ public class UndoManager
 
         // switch the doc's view to form alive mode (so the button will actually work)
         m_currentDocument.getCurrentView().dispatch( ".uno:SwitchControlDesignMode" );
+        XToolkitExperimental xToolkit = UnoRuntime.queryInterface(
+                XToolkitExperimental.class,
+                getORB().createInstance("com.sun.star.awt.Toolkit"));
+        xToolkit.processEventsToIdle();
 
         // click the button
         m_callbackCalled = false;