I wanted to add this tool for years and always forget. This command line option:
```
$ godot.exe -e --debug-canvas-item-redraw
```
Allows to see when a canvas item is redrawn. This helps find out if something
in the UI is refreshing in a way it should not. Examples as such:
* Signals causing more of the UI to redraw.
* Container resizing causes more UI elements to redraw.
* Something using a timer is redrawing all time time, which can go unnoticed.
To my surprise, the editor UI is redrawing very efficiently. There is some
weird stuff with the scene tabs, redrawing when the inspector changes but most
things for the most part are fine.
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