SetFocus fails on Windows, when called from HTMLViewer in a Container?

I have an app with a container control, with an HTMLViewer control in it. Below this container control is another container control with a text area in it. The HTMLViewer displays a list. When a user clicks on a link (a row in the list), that is detected, and an RB method does various things. One of those things is to put focus in the text area below. (so that a user can start entering data immediately).

So, this works fine on OS X. It doesn’t work at all on Windows. If I hit tab after that, the text area will have focus, with the cursor blinking, and text input accepted. So, it seems to be partially working.

I don’t have anything else around that uses setFocus, so if something is stealing focus, it’s not in my code. I’ve tried various things inspired by various RB forum posts: disabling the HTMLViewer before changing focus, disabling the container the HTMLviewer is in, turning around 3 times counterclockwise before lying down, etc.

This is with 2012r2.1.