GUI: copying functionality is frustrating

[c12hz]

Small UX nitpicks but:

• when you right click on any message the 'Copy' button popup appears and it's impossible to make it disappear by clicking anywhere else on the GUI, so if you right clicked by accident you are still forced to copy the message just to make the popup disappear. Could be especially frustrating if you accidentally right click on something sensitive. Clicking somewhere else on the window should make the 'Copy' popup disappear.
• after copying, the popup bar appears at the bottom of the window and covers up the message input and 'send' button, making it impossible to write messages until that bar disappears. I would move it to the top of the window instead of the bottom as the top of the window doesn't contain anything as important.

Note: I'm planning to work on this and a few other GUI things in the near future and submit a PR, but posting an issue for clarity.