Code holiday commit:

- fix: user pref, window title was reset to 'Blender' on tab usage

- Undo history menu back:
  - name "Undo History"
  - hotkey alt+ctrl+z (alt+apple+z for mac)
  - works like 2.4x, only for global undo, editmode and particle edit.

- Menu scroll
  - for small windows or screens, popup menus now allow to display
    all items, using internal scrolling
  - works with a timer, scrolling 10 items per second when mouse 
    is over the top or bottom arrow
  - if menu is too big to display, it now draws to top or bottom, 
    based on largest available space.
  - also works for hotkey driven pop up menus.

- User pref "DPI" follows widget/layout size
  - widgets & headers now become bigger and smaller, to match 
    'dpi' font sizes. Works well to match UI to monitor size.
  - note that icons can get fuzzy, we need better mipmaps for it

source/blender/editors/interface/interface_panel.c

@@ -334,10 +334,13 @@ static void uiPanelPop(uiBlock *UNUSED(block))
 void UI_DrawTriIcon(float x, float y, char dir)
 {
 	if(dir=='h') {
-		ui_draw_anti_tria( x-3,y-5, x-3,y+5, x+7,y );
+		ui_draw_anti_tria( x-3, y-5, x-3, y+5, x+7,y );
 	}
-	else {
-		ui_draw_anti_tria( x-5,y+3,  x+5,y+3, x,y-7);	
+	else if(dir=='t') {
+		ui_draw_anti_tria( x-5, y-7, x+5, y-7, x, y+3);	
+	}
+	else { /* 'v' = vertical, down */
+		ui_draw_anti_tria( x-5, y+3, x+5, y+3, x, y-7);	
 	}
 }