Bug 175664 [Mac] Unexpected internal exception occurs when invoke expression builder
Description: There are two problems: 1. "fx" button (Click this button to invoke Expression Builder) could not be displayed correctly, nothing displayed in the button. 2. Click on the button, an unexpected internal exception occurs. Version:2.2.0.v20070205 Steps to reproduce: 1.Insert a Data item to the layout. Click "fx" button to invoke the expression builder, although on Mac "fx" button could not display correctly. Error log: Argument cannot be null Plug-in Provider: Eclipse.org Plug-in Name: BIRT Designer UI Plug-in ID: org.eclipse.birt.report.designer.ui Error Code: Error.GUIException.invokedByUnexpectedException Error Message:Argument cannot be null
UI/org.eclipse.birt.report.designer.ui/src/org/eclipse/birt/report/designer/internal/ui/util/UIUtil.java
* 
	 * @return the length in pixels
	 */
	public static int getMaxStringWidth( String[] strArray, Control control )
	{
		int maxWidth = 0;
		for ( int i = 0; i < strArray.length; i++ )
		{
			int width = getStringWidth( strArray[i], control );
			maxWidth = maxWidth >= width ? maxWidth : width;
		}
		return maxWidth;
	}
	/**
	 * Returns if current active editor is reportEditor.
	 * 
	 * @return true if current active editor is reportEditor, or false else.
	 */
	public static boolean isReportEditorActivated( )
	{
		return getActiveReportEditor( ) != null;
	}
	/**
	 * Returns the current active report editor. The same as getActiveEditor(
	 * true ).
	 * 
	 * @return the current active report editor, or null if no report editor is
	 *         active.
	 */
	public static FormEditor getActiveReportEditor( )