class Command;
class Toggle;
-ui::ToolButton toolbar_append_button( ui::Toolbar toolbar, const char* description, const char* icon, const Callback& callback );
+ui::ToolButton toolbar_append_button( ui::Toolbar toolbar, const char* description, const char* icon, const Callback<void()>& callback );
ui::ToolButton toolbar_append_button( ui::Toolbar toolbar, const char* description, const char* icon, const Command& command );
-ui::ToggleToolButton toolbar_append_toggle_button( ui::Toolbar toolbar, const char* description, const char* icon, const Callback& callback );
+ui::ToggleToolButton toolbar_append_toggle_button( ui::Toolbar toolbar, const char* description, const char* icon, const Callback<void()>& callback );
ui::ToggleToolButton toolbar_append_toggle_button( ui::Toolbar toolbar, const char* description, const char* icon, const Toggle& toggle );
#endif