in messenger/mailWindowOverlay.xul

in toolbarbutton 'button-mark' changed the order of menuitems to have 'allread' on top.

in mail3PaneWindowCommands.js
in function isCommandEnabled
added 'return true' after 'case "button_mark"' ( line 304 )

in function doCommand
moved 'case buttom_mark' together with 'case cmd_markAllRead'