RightClickOverlay: check focus before clearing selection_pos

[ChrisJohnsen]

I found myself sometimes needing to "exit twice" to exit out of a dig designation that didn't have a selection started.

Problem Reproduction

• optionally, boot DF from scratch
• monitor .selection_pos with gm-editor
  • gui/gm-editor buildreq.selection_pos, Alt-a to enable live updates
• if needed, set .selection_pos to (0,0,0) to simulate a fresh DF start
  • the values can be edited in gm-editor, or
    • :lua ~buildreq.selection_pos:assign(xyz2pos(0,0,0))
• start one of the other (non-building placement) modes covered by RightClickOverlay (e.g. dig designation), but don't start a selection
• trigger LEAVESCREEN or right-click
  • Expect: selection mode is exited
  • Result: selection mode remains active
    • the gm-editor window will show that .selection_pos was changed to (-30k,-30k,-30k)
• a second trigger of LEAVESCREEN or right-click
  • the overlay will let the input pass and DF will exit the mode

Alternate Fix

Just swapping the if and elseif mostly works okay and avoids having to do focus matching.

This works because all the components of selection_rect start at -30k in a fresh boot and this overlay makes sure the "start" components are -30k before exiting the modes that change them.

There would still be some edge cases though:

• cancelling some kinds of selection_rect selections while this overlay is (temporarily) disabled
  • DF leaves the selection_rect "start" parts set when cancelling stockpile, zone, burrow selections
• new selection_rect uses in DF that this overlay hasn't been updated to also handle

Either could create a "cancel input suppressed" situations for building placement mode.

[myk002]

This solution looks fine (with the focus string check). This only runs in response to a manual action, so performance isn't really an issue here.

Could you add a line to the Fixes section in the changelog?

[ChrisJohnsen]

Oops! Sorry for leaving out a changelog entry.