Cursor does not change on resize color legend

The cursor does not change shape when we rescale the color legend. Replicate as follows:

Windows or Linux Kitware binaries of 5.3.0-RC2, local server. Sources/ Wavelet. Apply. Surface and color by RTData.

Now, with the mouse, try to grab the top of the color legend and drag it smaller or larger. If you do so in exactly the correct place it works, but the cursor doesn't change shape (as it did in 5.1.2) to give you a hint when you are at the right spot.