Function if

source/script_gui.cpp:3926–3943

Set font unconditionally to simplify calculations, which help ensure that at least one item in the DropDownList/Combo is visible when the list drops down:

			// Set font unconditionally to simplify calculations, which help ensure that at least one item
			// in the DropDownList/Combo is visible when the list drops down:
			GUI_SETFONT // Set font in preparation for asking it how tall each item is.
			if (calc_control_height_from_row_count)
			{
				item_height = (int)SendMessage(control.hwnd, CB_GETITEMHEIGHT, 0, 0);
				// Note that at this stage, height should contain a explicitly-specified height or height
				// estimate from the above, even if row_count is greater than 0.
				// The below calculation may need some fine tuning:
				int cbs_extra_height = ((style & CBS_SIMPLE) && !(style & CBS_DROPDOWN)) ? 4 : 2;
				min_list_height = (2 * item_height) + GUI_CTL_VERTICAL_DEADSPACE + cbs_extra_height;
				if (opt.height < min_list_height) // Adjust so that at least 1 item can be shown.
					opt.height = min_list_height;
				else if (opt.row_count > 0)
					// Now that we know the true item height (since the control has been created and we asked
					// it), resize the control to try to get it to the match the specified number of rows.
					// +2 seems to be the exact amount needed to prevent partial rows from showing
					// on all font sizes and themes when NOINTEGRALHEIGHT is in effect:
					opt.height = (int)(opt.row_count * item_height) + GUI_CTL_VERTICAL_DEADSPACE + cbs_extra_height;
			}
			MoveWindow(control.hwnd, opt.x, opt.y, opt.width, opt.height, TRUE); // Repaint, since it might be visible.
			// Since combo's size is created to accommodate its drop-down height, adjust our true height
			// to its actual collapsed size.  This true height is used for auto-positioning the next