Consider options for auto-closing debugger frames

[martinmcclure]

It is really nice to be able to have multiple debugger frames open at once, but even on a large screen the number of usefully open frames is fairly small, and having to manually close frames that are less useful is tedious.

We should consider allowing some debugger frames to be automatically closed in some circumstances.

One option is to automatically close any automatically-opened frame when the user selects a frame. Some times when a frame is automatically opened are

• Stopping for an exception
• Stopping for a breakpoint
• Stepping into a new method

These frames could be automatically closed when a frame is selected, or especially when automatically opening another frame.

Some thought needs to be given to whether modifier keys could change this, or whether to add a UI element for making a frame "sticky" and for seeing what the stickiness of an open frame is.