cs_panel.py: Fix behavior when there are overlapping definitions.
All panel definitions were being processed. If for some reason
a panel id was used twice, the second would still be added to the
stack navigation list (self.panels). The same would occur if a
given monitor:position slot had already been filled.
This would break navigation when switching between panels -
the button handlers would try to select pages from the stack
that weren't in it.
If any bad definitions are found, they're removed from 'panels-
enabled'
cs_panel.py: Set the step amount to 1 for panel heights.
This is stored as a str(int), but the default step for a Range
widget is calculated here to 0.8, so every so often the display
may stop matching what's actually being stored.
Clearing the attention flash on an already focused window was
unintuitive, since it would require the user unfocusing the window and
focusing it again. Since the user is already focused on the window,
just don't flash for its attention in the first place.
