Bug 136244 [Dialogs] PopupDialog - API - overriding default colors should be simpler
PopupDialog has protected methods that allow you to dictate which controls in the dialog should have their foreground/background color set. However, it is not simple to override the colors themselves. The method applyColors is private, and in order to use applyForegroundColor(...), etc., you must override createContents to ensure that the subclasses' colors get set after the default colors. Instead, the method applyColors should either be made protected, or it should call protected methods that specify the foreground and background color, rather than assuming it is always the system info colors.
bundles/org.eclipse.jface/src/org/eclipse/jface/dialogs/PopupDialog.java
*            the contents composite
	 */
	private void applyColors(Composite composite) {
		applyForegroundColor(JFaceResources.getColorRegistry().get(
				JFacePreferences.CONTENT_ASSIST_INFO_FOREGROUND_COLOR),
				composite, getForegroundColorExclusions());
		applyBackgroundColor(JFaceResources.getColorRegistry().get(
				JFacePreferences.CONTENT_ASSIST_INFO_BACKGROUND_COLOR),
				composite, getBackgroundColorExclusions());
	}
	/**
	 * Apply any desired fonts to the specified composite and its children.
	 * 
	 * @param composite
	 *            the contents composite
	 */
	private void applyFonts(Composite composite) {
		Dialog.applyDialogFont(composite);
	}
	/**
	 * Set the specified foreground color for the specified control and all of
	 * its children, except for those specified in the list of exclusions.
	 * 
	 * @param color
	 *            the color to use as the foreground color
	 * @param control
	 *            the control whose color is to be changed
	 * @param exclusions
	 *            a list of controls who are to be excluded from getting their
	 *            color assigned