Unfortunately, this patch doesn’t report touchscreen coordinates according to window size/resolution which is to be considered as an issue.
This behavior is for example different on Android platform where touch events coordinates are calculated according to screen size and resolution and reported as well.
So I propose to add this fix in SDL implementation for the following video drivers as it was done for Android:
That way, touch events will report mouse motion event with right coordinates, so your SDL application will behave in the same way whatever you use a mouse or a touchscreen to control it.
Waiting for your comment to get it in the next 2.0.10 release…