Various ui fixes:
- panel drawing now correctly follows scaled view
- made imagewindow buttons using TH_PANEL color back (was too dark)
- click on open/close panel was wrong
- menu items disabling now draws correct
- curve/hsv widgets didn't draw on right locations
- numsliders have nicer interior slider decoration
- new type TOGBUT to enforce old style toggle button (not new type
'option button' with checkmark
- (temp) disabled live updating while using Curve widget, was
too slow to be fun. Needs general solution :)
5cb480cef4