TTXAlwaysOnTop -- Tera Term keeps a window always on top. Feature: "Always on top" menu is added on Tera Term control menu. If a user selects this menu, Tera Term keeps a window always on top. If a user reselects the menu, this feature is canceled. Description: SetWindowPos API specified with HWND_TOPMOST parameter is called againt Tera Term window. Tera Term internal implementation is not modified. Bug: Not support TEK window.