Set canvas to window size
Use case
The canvas resizing feature lets me manually type in the size of the canvas in pixels. It would be useful to have a function/button to set this to the available window space, i.e. the size of the window minus all the toolbars. This would allow me to immediately use the most of my screen space for drawing.
Suggested solution
A button next to the width/height fields to "Fit to window".

Possible drawbacks
This might not be useful to some users, who are often resizing or moving the window, so the button should not be too intrusive. Also, the size would be different depending on the number of open files/tabs.
Possible alternatives
Manually setting the correct size and then setting these as the default value.
the window size isn't known when the first image is created so that feature can't be here. I had a similar problem last year when i tried to add an option "set optimal zoom by default"
as an option of the "crop" tool maybe? it doesn't really simplify the manipulation tho
otherwise yes the simplest solution possible is for you is to manually type the values for your screen in the inputs
I would even go beyond that, do not ask a picture size at all ! You could go for a 16/9 ration (1920x1080) by default, in the backgrount, and then allow to zoom in and zoom out. This would actually increase or decrease the actual picture size. And on save set the appropriate size. No need to ask, and you could have kind of an infinite dashboard, I would love this feature.
that would be a very different app? it's an image editor, the files it opens have a size, the tools include scaling and croping, etc.
transforming the app into an infinite whiteboard would mean removing the most used features
I'm not so sure, I find myself...hmm constrained by the canvas' border ? I think contrary to real physical canvas, we could have a dynamic canvas size, automatically. How would you suggest to go about this as straighforwardly as possible ? I know some python. Thank you.
There is no straightforward way to do this, almost all parts of the app would be heavily impacted