In Graph pane, when branches are grouped due to display width, enable right-click menu to access other branches

In the Graph pane, when there are too many branches on a commit the "less important" ones are grouped into an "X branches" button:

If you click on this button, it shows the extra branches in a popup:

But, there's no way to take actions on these additional branches; you must look for them in the Branches pane. Three things get in the way of manipulating them directly in the Graph pane: 

• If you right-click on the "X branches" button then a menu appears, but the "Check Out..." choice brings up a dialog where you must either create a new branch or work on a detached head
• As soon as you move your cursor off of the "X branches" button the popup goes away
• Even if the popup remained, it's unlikely that right-clicking on a branch name would bring up a menu and let you operate on that branch.

Proposal:

• If you right-click on the "X branches" button, show an actual popup menu listing the available branches
• Each branch name has a submenu giving the usual options for right-clicking such a branch