Tk Source Code

event generate ... -warp 1 sometimes moves the pointer one pixel short of the requested position on Windows:

event generate {} <Motion> -warp 1 -x 100 -y 1
update idletasks
winfo pointerxy .

On a 800x600 screen this returns 100 0 instead of 100 1. On a 3840x2160 screen, warping to 20 20 gives 19 20, and test bind-34.2 fails.

TkSetCursorPos() converts the position to the normalized coordinates of SendInput() with rounding to nearest, but Windows converts them back with rounding down, so some positions map to the previous pixel. This happens on most screen sizes, e.g. for 7 x values on a 1920 pixels wide screen and for 28 on a 3840 pixels wide screen.

Proposed fix in branch win-warp-rounding: round up instead.

Now merged to [36a85716|trunk], core-9-0-branch and core-8-6-branch