Region scrollbar fix!

Now scrollbars correctly hide and show, making space for the actual contents
in a region. It solves several old hacks, and puts view2d code a bit more
back in control as well. 

Implementation notes:

- The view2d mask feature is working again
- The #define V2D_SCROLL_HORIZONTAL_HIDE means: "turn on hiding".
- Code for UI_view2d_region_reinit() is enforcing better standard view settings

But... two hack/patches needed to be added:

- Region panel drawing: if after generating the button panels it appears
  a scroller hides or reveils, it calls all the generating code again.
  (a simple scale doesn't work due to rounding differences in layout code)

- View2d code that maps 'tot' and 'cur' rects: if this code detects that
  the mask changes, it calcs the map code again.

Also a bugfix (issue in 2.65)

- The left/bottom area split widget was drawing 1 pixel too large sometimes, 
  leaving bad trails on moving area dividers.

1 files changed, 2 insertions, 0 deletions

diff --git a/source/blender/editors/interface/interface.c b/source/blender/editors/interface/interface.c
index 25f85883d9c..1d26cbd344b 100644
--- a/source/blender/editors/interface/interface.c
+++ b/source/blender/editors/interface/interface.c
@@ -2666,6 +2666,8 @@ static uiBut *ui_def_but(uiBlock *block, int type, int retval, const char *str,
 	
 	/* we could do some more error checks here */
 	if ((type & BUTTYPE) == LABEL) {
+		if ((poin != NULL || min != 0.0f || max != 0.0f || (a1 == 0.0f && a2 != 0.0f) || (a1 != 0.0f && a1 != 1.0f)))
+			printf("blah\n");
 		BLI_assert((poin != NULL || min != 0.0f || max != 0.0f || (a1 == 0.0f && a2 != 0.0f) || (a1 != 0.0f && a1 != 1.0f)) == FALSE);
 	}