Intended behavior of Variables window? #9

There's a few things I notice about the Variables window:

• The list variables (i.e. which labels) is only updated automatically when loading a source file in a new/empty session or when opening another session, not when recompiling, opening another source file, or when opening a new session.
• Every label or #define is selected, rather than just those corresponding to certain pseudo-opcodes (e.g. ds, rmb, fcc), so it's a long list by default for any programs using e.g. Reg9s12.h; although I can see how it's necessary to include labels for other cases--given the nature of labels, it might be hard to tell exactly what is data (variable or array), instructions, or in cases such as self-modifying code, both.

I'm not sure how much of this is intentional; I have yet to look closely at how this is implemented in auto_select_variables(). So at a minimum this might be an undocumented feature.

Since one might edit the Variables window by hand, it's fine to leave it as it is where it doesn't reselect, but it may be useful to add a button that allows the user to invoke variable reselection.