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, 4 insertions, 5 deletions

diff --git a/source/blender/editors/space_action/space_action.c b/source/blender/editors/space_action/space_action.c
index c5f3ccee101..e0ca589c1fb 100644
--- a/source/blender/editors/space_action/space_action.c
+++ b/source/blender/editors/space_action/space_action.c
@@ -219,6 +219,9 @@ static void action_channel_area_init(wmWindowManager *wm, ARegion *ar)
 {
 	wmKeyMap *keymap;
 	
+	/* ensure the 2d view sync works - main region has bottom scroller */
+	ar->v2d.scroll = V2D_SCROLL_BOTTOM;
+	
 	UI_view2d_region_reinit(&ar->v2d, V2D_COMMONVIEW_LIST, ar->winx, ar->winy);
 	
 	/* own keymap */
@@ -231,7 +234,6 @@ static void action_channel_area_draw(const bContext *C, ARegion *ar)
 	/* draw entirely, view changes should be handled here */
 	bAnimContext ac;
 	View2D *v2d = &ar->v2d;
-	View2DScrollers *scrollers;
 	
 	/* clear and setup matrix */
 	UI_ThemeClearColor(TH_BACK);
@@ -247,10 +249,7 @@ static void action_channel_area_draw(const bContext *C, ARegion *ar)
 	/* reset view matrix */
 	UI_view2d_view_restore(C);
 	
-	/* scrollers */
-	scrollers = UI_view2d_scrollers_calc(C, v2d, V2D_ARG_DUMMY, V2D_ARG_DUMMY, V2D_ARG_DUMMY, V2D_ARG_DUMMY);
-	UI_view2d_scrollers_draw(C, v2d, scrollers);
-	UI_view2d_scrollers_free(scrollers);
+	/* no scrollers here */
 }