Developer tools window to debug toolbox open in current tab.

debug-toolbox.js

/*
* Running this scratchpad will open a Developer Tools window that's debugging
* the currently selected tab's toolbox.
*/

Cu.import("resource:///modules/devtools/Target.jsm");

let target = TargetFactory.forTab(gBrowser.selectedTab);
let toolboxToDebug = gDevTools.getToolbox(target);
let tbTarget = TargetFactory.forWindow(toolboxToDebug.frame.contentWindow);

let toolbox = gDevTools.showToolbox(tbTarget, "styleeditor", "window");