Bug 75711 AstProvider should not create AST if requested by SelectionListenerWithASTManager
3.1 M2 If SelectionListenerWithASTManager waits for an AST and the editor closes we should not create an AST for that one but return null instead.
org.eclipse.jdt.ui/ui/org/eclipse/jdt/internal/ui/javaeditor/JavaEditor.java
Point minLocation= getMinimumLocation(text, offset, length);
			Point maxLocation= getMaximumLocation(text, offset, length);
	
			int x1= minLocation.x;
			int x2= minLocation.x + maxLocation.x - minLocation.x - 1;
			int y= minLocation.y + text.getLineHeight() - 1;
			
			GC gc= event.gc;
			if (fColor != null && !fColor.isDisposed())
			gc.setForeground(fColor);
			gc.drawLine(x1, y, x2, y);
		}
		private boolean includes(IRegion region, IRegion position) {
			return
				position.getOffset() >= region.getOffset() &&
				position.getOffset() + position.getLength() <= region.getOffset() + region.getLength();
		}
		private Point getMinimumLocation(StyledText text, int offset, int length) {
			Point minLocation= new Point(Integer.MAX_VALUE, Integer.MAX_VALUE);
	
			for (int i= 0; i <= length; i++) {
				Point location= text.getLocationAtOffset(offset + i);
				
				if (location.x < minLocation.x)
					minLocation.x= location.x;			
				if (location.y < minLocation.y)
					minLocation.y= location.y;			
			}