Can't see customize toolbar icon
===

I want a icon in the Browsertoolbar - that works. See image one

http://s18.postimage.org/njeyj7ekn/Neues_Bild.png

But why I can't see the icon in the icon selection box?

http://s18.postimage.org/pzgrx1wnb/Neues_Bild_1.png

I get only the toolbar icons.

Here are my code snippets:

XUL:


    <toolbarpalette id="BrowserToolbarPalette">
          <toolbarbutton id="megxbar-ide-button" label="&MegxBarSidebar.label;" class="toolbarbutton-1 chromeclass-toolbar-additional" tooltiptext="&MegxBarSidebar.label;" observes="viewSidebar_MegxBar" />
       </toolbarpalette>



CSS:


    @namespace url('http://www.mozilla.org/keymaster/gatekeeper/there.is.only.xul');

    #megxbar-ide-button {
      list-style-image: url(chrome://MegxBar/skin/megxbar24.png);

    }

    toolbar[iconsize="small"] #megxbar-ide-button {

        list-style-image: url(chrome://MegxBar/skin/megxbar16.png);

       }



And I have one more question. How could I set the icon per default on that positon of picture number 1? I mean, I start the browser an see the icon of the extension after the first restart after the installation.