Currently it is not possible resize the floating participant window while sharing via the API.
As our integration is on a large screen with no user input there is no way for us to make the participant thumbnails a usable size (they’re always ~250px wide, which is tiny on these screens).
Because this window manages it’s own size/position, it’s also not possible to do this via the win32 APIs.
It is possible to reposition this window using ‘MoveFloatVideoWnd’.
This would probably also require exposing the ‘Grid’ layout of this window, which is currently not available via the SDK, only via the UI. Originally I though that the ‘SwitchFloatVideoToGalleryMod’ method would do this, but this actually puts it into the ‘thumbnails’ mode (as it’s called in the UI).