Selecting UI controls
There are a few different ways to select UI controls.
- Clicking on a UI control selects it
 - Dragging a rectangle which encloses many UI controls selects them
 - SHIFT+ CLICK on a control adds it to the selection
 - CTRL/⌘+ CLICK on a selected control removes it from the selection
 - Hold ALT to ignore items behind the mouse and drag-select
 
When you select a control, you'll see it enclosed in a blue rectangle with handles at the edges and corners.
To add a control that is behind another control to the selection, right-click on the top control and hold down SHIFT to bring up a menu that allows you to add controls behind it.