I know how to insert a new toolbarbutton to call a plugin. Is it possible to extend such a toolbarbutton, so that i have in addition to the normal button a submenu on the right side of this button? For example when im in the E-Mail List view and i have selected some e-mail, the button "answer all" becomes active. This "answer all" button has 2 functions. First when i click the button itself, i can answer all people in this mail and second, there is a small submenu on the right side of this button, if i click this, the submenu pops out and i can select "anser all" or "answer list". Now i would add such a submenu function also to a button in the toolbar. How can i do this?