Drag causes text selection

[fulldecent]

This is not a problem in actual terminal emulator.

But on the web, if you are dragging a window, then the browser will show it as a text selection from the original location to the final location.

We could solve this just for the browser by doing: 1) show a clear div over everything 2) intercept clicks/drags/scrolls and play through to the TUI layer.