Bug 49323: Make shift-delete work with toolbar button, patch by Bruno 'Aqualon' Escherl <aqualon@aquachan.de> and Neil, r=bienvenu, NPOTDB

mailnews/base/resources/content/mailWindowOverlay.xul

@@ -1869,7 +1869,7 @@
                  observes="button_junk"/>
       </deck>
 
-      <toolbarbutton class="toolbarbutton-1" id="button-delete" label="&deleteButton.label;" tooltiptext="&deleteButton.tooltip;" observes="button_delete" oncommand="goDoCommand('button_delete')"/> 
+      <toolbarbutton class="toolbarbutton-1" id="button-delete" label="&deleteButton.label;" tooltiptext="&deleteButton.tooltip;" observes="button_delete" oncommand="goDoCommand(event.shiftKey ? 'cmd_shiftDelete' : 'cmd_delete')"/>
       <toolbarbutton type="menu-button" id="button-mark" class="toolbarbutton-1" label="&markButton.label;" hidden="true" oncommand="goDoCommand('button_mark')"
                   observes="button_mark" tooltiptext="&markButton.tooltip;">  
             <menupopup onpopupshowing="InitMessageMark()">