Preferences -> Global Preferences -> Window, click to modify Window Geometry, then Cancel.
You get the error:
Error executing dialog::specialSet::geometry {prefs::dialogs::_setPrefValue standard windowGeometry} {view378 {Window,Window Geometry} {geometry {prefs::dialogs::_setPrefValue standard windowGeometry}}}
This is fixed now.
Changes committed to the repository (rev. 1286 (sourceforge.net)). Note that the core must be rebuilt due to changes (unrelated to this ticket) in the WebView command and the Help Viewer.