"Attach as tab to" and "More Actions" do not have accelerator keys.
Access to items in these submenus requires either mouse or arrow keys.

Reproducible: Always

Steps to Reproduce:
1. Alt+F3, right-click on titlebar, or left click the application icon in the titlebar
2. attempt to access actions in the submenus without using mouse or arrow keys
Actual Results:  
mouse or arrow keys are required, slowing down the action.

Expected Results:  
something like <alt>+<F3>,<m>,<a> (for example) should shade the window without needing to remove one's hands from the keyboard