The theme "default" on XC/X2 or "cube_default" on XC was set to "Theme set for admin".

Any modules but altsys 0.55a (and system default modules) are not installed on XOOPS.
All 4 images of opened/closed buttons are displayed normally with Firefox2 and Opera9.

flow and conditions with XOOPS Cube Legacy 2.1.2 or XOOPS 2.0.16a JP:
01. template "block_admin_menu.html" not modified (altsys original) and set to default
02. theme "default" on XC/X2 or "cube_default" on XC set to "Theme set for admin" and submitted
03. XOOPS_ROOT_PATH/templates_c/* deleted, but index.html
04. browser's cache cleared
05. web page reloaded
06. white plus image (adminmenu_closed.gif) clicked
07. white minus image (adminmenu_opened.gif) not displayed
08. orange minus image (adminmenu_selected_opened.gif) clicked
09. orange plus image (adminmenu_selected_closed.gif) not displayed
10. template "block_admin_menu.html" modified as shown below and set to default
11. white plus image (adminmenu_closed.gif) clicked
12. white minus image (adminmenu_opened.gif) displayed
13. orange minus image (adminmenu_selected_opened.gif) clicked
14. orange plus image (adminmenu_selected_closed.gif) displayed

modified:
(XOOPS_TRUST_PATH/libs/altsys/templates/)block_admin_menu.html: added to line 14 or somewhere