Note, this was reported as a bug however it's a TODO (wasn't supported in 2.7x).
Operating system: Windows-10-10.0.17763 64 Bits
Graphics card: GeForce GTX 1070/PCIe/SSE2 NVIDIA Corporation 4.5.0 NVIDIA 430.39
Broken: version: 2.80 (sub 60), branch: master, commit date: 2019-04-29 17:52, hash: rB047081841113
Worked: (version before the click transparent passthrought)
Short description of error
Cannot drag on the tabs to select other tab like normal tab behavior on Blender.
Exact steps for others to reproduce the error
-Press 'N' on the 3D View.
-Try to drag on the tabs on the "WM_OT_context", the result is the box selection.
See attached gif (ignore the mouse cursor offset, that is due to 4k display with only 125% scale applied.)