Robot Steering plugin not visible in RQT

Question

I have a ROS2 Iron environment installed from the ros-iron-desktop package. The Robot Steering plugin isn't visible in RQT, even after installing ros-iron-rqt-robot-steering. Trying to start it on its own fails with the below error message:

$ rqt_robot_steering
QStandardPaths: XDG_RUNTIME_DIR not set, defaulting to '/tmp/runtime-user'
qt_gui_main() found no plugin matching "rqt_robot_steering.robot_steering.RobotSteering"
try passing the option "--force-discover"
Warning: class_loader.ClassLoader: SEVERE WARNING!!! Attempting to unload library while
objects created by this loader exist in the heap! You should delete your objects before
attempting to unload the library or destroying the ClassLoader. The library will NOT be
unloaded.
         at line 127 in ./src/class_loader.cpp

Answer 1

It turns out that all I had to do was follow the instructions in the error message itself, that is try the --force-discover option:

$ rqt --force-discover

After which the Robot Steering plugin was visible in RQT and could be loaded normally. Subsequent calls of rqt without the option also worked correctly.