Add support for pasting in plain text with additional key in shortcut

[drej1]

Hi, it would be great if it was possible to paste in richtext by default but add possibility to paste in plaintext. Eg. when navigating through history and instead of hitting enter you hit command + enter (commnand + mouse click) (or control + enter whatever) it would paste plain text, and by hitting only enter it would paste richtext.

Thanks