Some UI tweaks as listed by William

(http://wiki.blender.org/index.php/BlenderDev/Blender2.5/Todo/UserInterface)

* Removed panel docking. "It is too easy to do by accident when reordering panels, is very hard to control and use, and has no real benefit."

* Scoll bars have minimum size now, so that the 'thumb' doesn't disappear in long lists.

source/blender/editors/interface/interface_panel.c

@@ -963,6 +963,7 @@ static void check_panel_overlap(ARegion *ar, Panel *panel)
 	}
 }
 
+#if 0 // XXX panel docking/tabbing code that's no longer used
 static void test_add_new_tabs(ARegion *ar)
 {
 	Panel *pa, *pasel=NULL, *palap=NULL;
@@ -1016,6 +1017,7 @@ static void test_add_new_tabs(ARegion *ar)
 		pa= pa->next;
 	}
 }
+#endif
 
 /************************ panel dragging ****************************/
 
@@ -1382,7 +1384,12 @@ static void panel_activate_state(const bContext *C, Panel *pa, uiHandlePanelStat
 
 	if(state == PANEL_STATE_EXIT || state == PANEL_STATE_ANIMATION) {
 		if(data && data->state != PANEL_STATE_ANIMATION) {
-			test_add_new_tabs(ar);   // also copies locations of tabs in dragged panel
+			/* XXX:
+			 *	- the panel tabbing function call below (test_add_new_tabs()) has been commented out
+			 *	  "It is too easy to do by accident when reordering panels, is very hard to control and use, and has no real benefit." - BillRey
+			 * Aligorith, 2009Sep
+			 */
+			//test_add_new_tabs(ar);   // also copies locations of tabs in dragged panel
 			check_panel_overlap(ar, NULL);  // clears
 		}