Godot version:
3.2.2
Issue description:

It should be probably made bigger, so it doesn't expand awkwardly when title is too long.
EDIT:
In case someone doesn't know, the dialog appears when you drag and drop a texture into 2D view, while holding Alt.
Hello, I am interested in working on this issue. I read through the setup for Godot engine, are there any more places I can look to for getting started? Any pointers from you would be helpful! Thank you.
@Insiyaa You can give it a fixed width in constructor of CanvasItemEditorViewport.
https://github.com/godotengine/godot/blob/a474926aca8a5da810f8cf546902c6da7286b254/editor/plugins/canvas_item_editor_plugin.cpp#L6368
For contributing, read this :)
Hello,
I also started working on this issue yesterday and I am interested in contributing more to the project.
I have submitted my first PR and as I am new to this process, any feedback will be helpful.
@Insiyaa Sorry I didn't see that you were interested in this issue too. I am not sure how to avoid this in the future, is there a way to see who's currently working on an issue?
For compiling the engine, you can use this link https://docs.godotengine.org/en/latest/development/compiling/index.html
Most helpful comment
@Insiyaa You can give it a fixed width in constructor of CanvasItemEditorViewport.
https://github.com/godotengine/godot/blob/a474926aca8a5da810f8cf546902c6da7286b254/editor/plugins/canvas_item_editor_plugin.cpp#L6368
For contributing, read this :)