In eclipse its possible to position the mouse cursor on an item and press Alt+Shift+F1 to open the PluginSpy and get info on the source files for the focused item.
But how do I inspect (find all org.eclipse.ui.menus contributions for a menu) eg. the menu contributions that make up the File menu in eclipse?
Eg. is it possible to find the plugin that add the “Recent Files list” in the bottom of the file menu?
Alt+Shift+F2 will open the “Plugin Menu Spy”, you can use that to get information on menus.
Using this I found out that the active contribution item identifier for the list in question is “reopenEditors”. Googling for that led me to this. This probably answers your question :).