Is there a keyboard shortcut in Firefox to paste the Unix "primary selection" clipboard, not the Firefox one?

I run Linux, and am used to selecting text with the mouse to copy and pressing Shift+Insert to paste. (This uses an alternate clipboard known as the "Primary Selection".)

This seems to work in every application besides Firefox. Firefox uses a different clipboard, where Ctrl+C copies and Ctrl+V pastes. Is there a keystroke or configuration change I can do to make Firefox paste from the Unix "primary selection" clipboard -- the one it pastes from when I click the middle mouse button?

Note: I'm looking for a keyboard shortcut, not a mouse action.

X11 has multiple clipboards: Selecting text with the mouse fills the "Primary Selection" and clicking the middle button inserts it. For Ctrl-V/Ctrl-C most programs use the "Clipboard", Shift-Ins seems to sometimes use the Primary Selection, sometimes the Clipboard.

So it's easier to not use Shift-Ins but either the Mouse or Ctrl-V/Ctrl-C to copy text between different applications.

You can bind the following command to a key, it should make your firefox selection available to other programs:

xsel -b|xsel

and vice versa

xsel|xsel -b