Split cursor appears but has no effect in QDockWidget with size constraints

This situation presents itself when two QWidgets are docked next to each other and the other one has a fixed size. Bringing the mouse cursor on top of the split between these widgets causes split cursor to appear, but, because the other QDockWidget is fixed in size, no stretching can take place. Yet, the cursor indicates otherwise and this gives the user a false intuition about how the UI works. This is a design choice with shortcomings rather than a technical problem (a bug) in functionality.

This can be observed in QtCreator (please see the image attached).