AddonListener
method overview void onenabling(in addon addon, in boolean needsrestart) void onenabled(in addon addon) void ondisabling(in addon addon, in boolean needsrestart) void ondisabled(in addon addon) void oninstalling(in addon addon, in boolean needsrestart) void oninstalled(in addon addon) void onuninstalling(in addon addon, in boolean needsrestart) void onuninstalled(in addon addon) void onoperationcancelled(in addon addon) void onpropertychanged(in addon addon, in string properties[]) methods onenabling() called when an add-on is about to be enabled.
... void oninstalling( in addon addon, in boolean needsrestart ) parameters addon the addon that is being installed needsrestart true if an application restart is necessary for the change to take effect oninstalled() called when an add-on has been installed.
... void oninstalled( in addon addon, ) parameters addon the addon that has been installed onuninstalling() called when an add-on is about to be uninstalled.

nsIWebappsSupport
1.0 66 introduced gecko 2.0 inherits from: nsisupports last changed in gecko 2.0 (firefox 4 / thunderbird 3.3 / seamonkey 2.1) method overview void installapplication(in wstring title, in wstring uri, in wstring iconuri, in wstring icondata); boolean isapplicationinstalled(in wstring uri); methods installapplication() this method installs a web application.
... isapplicationinstalled() checks is a web application is already installed.
... boolean isapplicationinstalled( in wstring uri ); parameters uri the uri of the web application.

IME handling guide
then, tabchild calls imestatemanager::oninstalledmenukeyboardlistener() in the remote process.