gui_toolkit 0.19.0

Added

• ui.menu_item(..., keep_open = true): choosing the item does not close the menu, for the switches of a settings menu (the check mark changes, the menu stays for the next one).
• ui.set_menu_item_height(em): the height of the items of the menus built from then on, in em (default MENU_ITEM_EM, 2.2; 0 puts it back). A dense tool panel sets it while it builds its menus.
• ui.menu_heading(text): a small weak title above a group of items of a menu (not an item: the keyboard skips it).
• Fixed: platform.open_window kept the window class name in the caller's allocator, so a window opened later (once that memory was reused) failed with "cannot find window class"; the name is a literal now.
• ui.use(state): selects the state the public procedures operate on, for programs that draw several windows with a state each.
• render.surface_create / surface_use / surface_destroy: a second window drawn by the same renderer (same device, textures, fonts), as a surface swapped in for the frames drawn to it (Direct3D 11).
• ui.tooltip_beside(): tooltip placed beside the pointer (its right, or its left when there is no room), centered on it, for the rows of a list or a table, where a tooltip below the pointer hides the rows under it.