Bug 36902 [preferences] IllegalArgumentException in JavaEditorHoverConfigurationBlock$3.keyReleased
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/preferences/JavaEditorHoverConfigurationBlock.java
Assert.isNotNull(store);
		fMainPreferencePage= mainPreferencePage;
		fStore= store;
	}
	/**
	 * Creates page for hover preferences.
	 */
	public Control createControl(Composite parent) {
		Composite hoverComposite= new Composite(parent, SWT.NULL);
		GridLayout layout= new GridLayout();
		layout.numColumns= 2;
		hoverComposite.setLayout(layout);
		GridData gd= new GridData(GridData.GRAB_HORIZONTAL | GridData.VERTICAL_ALIGN_FILL);
		hoverComposite.setLayoutData(gd);
		Label label= new Label(hoverComposite, SWT.NONE);
		label.setText(PreferencesMessages.getString("JavaEditorHoverConfigurationBlock.hoverPreferences")); 
		gd= new GridData(GridData.FILL_HORIZONTAL);
		gd.horizontalAlignment= GridData.BEGINNING;
		gd.horizontalSpan= 2;
		label.setLayoutData(gd);
		gd= new GridData(GridData.GRAB_HORIZONTAL | GridData.VERTICAL_ALIGN_FILL);
		
		fHoverList= new List(hoverComposite, SWT.SINGLE | SWT.V_SCROLL | SWT.BORDER);
		gd= new GridData(GridData.VERTICAL_ALIGN_BEGINNING | GridData.FILL_HORIZONTAL);
		gd.heightHint= convertHeightInCharsToPixels(parent, 10);
		fHoverList.setLayoutData(gd);
		fHoverList.addSelectionListener(new SelectionListener() {
			public void widgetSelected(SelectionEvent e) {
				handleHoverListSelection();
			}