Bug 323389 Prompt required when resetting perspectives from the perspective switcher
We prompt in 3.x, so we should prompt in 4.x.
bundles/org.eclipse.e4.ui.workbench.addons.swt/src/org/eclipse/e4/ui/workbench/addons/perspectiveswitcher/PerspectiveSwitcher.java
gc.drawPolyline(line2);
		gc.dispose();
		comp.setBackgroundImage(backgroundImage);
		if (oldBackgroundImage != null)
			oldBackgroundImage.dispose();
	}
	void dispose() {
		cleanUp();
		if (backgroundImage != null) {
			comp.setBackgroundImage(null);
			backgroundImage.dispose();
			backgroundImage = null;
		}
	}
	void disposeTBImages() {
		ToolItem[] items = psTB.getItems();
		for (int i = 0; i < items.length; i++) {
			Image image = items[i].getImage();
			if (image != null) {
				items[i].setImage(null);
				image.dispose();
			}
		}
	}
	public void setKeylineColor(Color borderColor, Color curveColor) {
		this.borderColor = borderColor;
		this.curveColor = curveColor;
	}
}