There is something odd going on with window resizing, but I can't quite put my finger on what's wrong. Let me explain.

Observation: before a window is resized, only the very bottom line of pixels actually triggers a resize!

Once a resize has been triggered successfully, the window does actually resize correctly.

Windows have a designated 19x19 pixel area that allows for resizing. See MouseInput.cpp:

        switch (widget->type)
        {
            case Ui::WidgetType::panel:
            case Ui::WidgetType::newsPanel:
            case Ui::WidgetType::frame:
                if (window->canResize() && (x >= (window->x + window->width - 19)) && (y >= (window->y + window->height - 19)))
                {
                    windowResizeBegin(x, y, window, widgetIndex);
                }

Could it be that we're not setting the initial dimensions for these widgets correctly in some windows, thereby affecting the handle?

I last noticed this while working on #3384, but have definitely noticed it in other windows. Will have to investigate further.