[Bug] `#editor` and `#selection` are broken if the active editor is in the background

[wenfangdu]

In the following picture, package.json is the #editor, but because it's in the background, copilot doesn't know anything about it: Same applies to #selection.

This doesn't hold true for terminal, even if the terminal is hidden, copilot stills knows what #terminalLastCommand and terminalSelection are.

People like me often use copilot chat in a non-split editor, #editor and #selection are completely broken in this case.