Method ControlCheckRadioButton

source/script_gui.cpp:9600–9643

void GuiType::ControlCheckRadioButton(GuiControlType &aControl, GuiIndexType aControlIndex, WPARAM aCheckType)
{
	GuiIndexType radio_start, radio_end;
	FindGroup(aControlIndex, radio_start, radio_end); // Even if the return value is 1, do the below because it ensures things like tabstop are in the right state.
	if (aCheckType == BST_CHECKED)
	{
		// Testing shows that controls with different parent windows never behave as though they
		// are part of the same radio group.  CheckRadioButton has been confirmed as working with
		// both non-dialog windows (such as Static/Text) and Tab3's tab dialog.  This is required
		// for this function to work on Radio buttons within a Tab3 control:
		HWND hDlg = GetParent(aControl.hwnd);
		// This will check the specified button and uncheck all the others in the group.
		// There is at least one other reason to call CheckRadioButton() rather than doing something
		// manually: It prevents an unwanted firing of the radio's g-label upon WM_ACTIVATE,
		// at least when a radio group is first in the window's z-order and the radio group has
		// an initially selected button:
		CheckRadioButton(hDlg, GUI_INDEX_TO_ID(radio_start), GUI_INDEX_TO_ID(radio_end - 1), GUI_INDEX_TO_ID(aControlIndex));
	}
	else // Uncheck it.
	{
		// If the group was originally created with the tabstop style, unchecking the button that currently
		// has that style would also remove the tabstop style because apparently that's how radio buttons
		// respond to being unchecked.  Compensate for this by giving the first radio in the group the
		// tabstop style. Update: The below no longer checks to see if the radio group has the tabstop style
		// because it's fairly pointless.  This is because when the user checks/clicks a radio button,
		// the control automatically acquires the tabstop style.  In other words, even though -Tabstop is
		// allowed in a radio's options, it will be overridden the first time a user selects a radio button.
		HWND first_radio_in_group = NULL;
		// Find the first radio in this control group:
		for (GuiIndexType u = radio_start; u < radio_end; ++u)
			if (mControl[u]->type == GUI_CONTROL_RADIO) // Since a group can have non-radio controls in it.
			{
				first_radio_in_group = mControl[u]->hwnd;
				break;
			}
		// The below can't be done until after the above because it would remove the tabstop style
		// if the specified radio happens to be the one that has the tabstop style.  This is usually
		// the case since the button is usually on (since the script is now turning it off here),
		// and other logic has ensured that the on-button is the one with the tabstop style:
		SendMessage(aControl.hwnd, BM_SETCHECK, BST_UNCHECKED, 0);
		if (first_radio_in_group) // Apply the tabstop style to it.
			SetWindowLong(first_radio_in_group, GWL_STYLE, WS_TABSTOP | GetWindowLong(first_radio_in_group, GWL_STYLE));
	}
}