This seems to work. Load the macro below and in the build window, do right click -> edit this menu and add the command to the menu. If you want to customise a menu that doesn't have an "edit this menu" option, you just need to find the name of the menu and edit it via macro -> menus.
_command void goto_editor_window_from_build() name_info(',')
{
int pl = p_line;
edit ("+b Build (.process)");
goto_line(pl);
}