Problem with MSComctlLib.Slider.2 slider control

[vernpace]

We have a project that requires extensive use of a slider control. We have tried a few (e.g. FoxySlider, ctl32_trackbar), but have found that the good old Microsoft Slider Control 6.0 (SP6) is the best for our purpose EXCEPT for the focus rectangle as shown below:

This is annoying. A possible solution to hide the focus rectangle is the SendMessage API using the WM_UPDATEUISTATE message along with both UIS_SET (low-order word) and UISF_HIDEFOCUS (high-order word) for the wParam parameter.

https://docs.microsoft.com/en-us/windows/win32/menurc/wm-updateuistate

Does anyone know how to construct the low-order and high-order words for the wParam parameter to be used with SendMessage? Bit shifting?