# Objective
- When viewport is set to the same size as the window on creation, when
adjusting to SizedFullscreen, the window may be smaller than the
viewport for a moment, which caused the arguments to be invalid and
panic.
- Fixes#12000.
## Solution
- The fix consists of matching the size of the viewport to the lower
size of the window ( if the x value of the window is lower, I update
only the x value of the viewport, same for the y value). Also added a
test to show that it does not panic anymore.
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