Cannot resize memcheck results panel on recent Qt versions

On recent Qt Creator builds it has become impossible to vertically resize the Memcheck results panel. Hovering over the usual vertical splitter location does not change the cursor to the resize icon and clicking and dragging to resize has no effect. The default height of the panel is also very small (only allow 1.5 lines of text), effectively making the feature unusable.

I can reproduce this on both Qt creator 4.7 and the prerelease versions of Qt Creator 4.8.