HTMLViewer (WebKit) stealing KeyDown


in one of our projects we have a problem which I unfortunately can’t reproduce in a small sample project.
We have our WinMain as a Document window. On this window there is a HTMLViewer placed.
If we open a subwindow (type Movable Modal) with a canvas on it then sometimes the HTMLViewer “steals” the KeyDown event of this Canvas.
The KeyDown sometimes simply doesn’t fire anymore on the canvas especially on return and backspace keys (but it doesn’t fire on the HTMLViewer either).
I know that the issue is the HTMLViewer because as soon as I delete the control or set the renderer to “Native” the issue doesn’t appear anymore.

Does anyone had a similar issue?