Bugfix #24343

Ancient 2.5 UI issue:

The button views in Property Editor have an internal storage, to ensure the view
on the buttons stays same when you switch contextes or select objects.

Bug was that - in case buttons were all scrolled invisible - sometimes no slider
was drawn to indicate that.

Discussion on whether this is a good feature or not: the only improvement would
be to store such settings even per object... but that's a feature creep I think.

source/blender/editors/screen/area.c

@@ -1663,11 +1663,9 @@ void ED_region_panels(const bContext *C, ARegion *ar, int vertical, const char *
 		v2d->scroll |= V2D_SCROLL_HORIZONTAL_HIDE;
 		v2d->scroll &= ~V2D_SCROLL_VERTICAL_HIDE;
 		
-		/* don't jump back when panels close or hide */
-		if (!newcontext)
-			y = MAX2(-y, -v2d->cur.ymin);
-		else
-			y = -y;
+		/* ensure tot is set correctly, to keep views on bottons, with sliders */
+		y = MAX2(-y, -v2d->cur.ymin);
+		
 	}
 	else {
 		/* for now, allow scrolling in both directions (since layouts are optimized for vertical,