Launch a remote EDA GUI over X forwarding without disturbing ssh masters

To open a remote GUI (e.g. a waveform debugger from an environment-modules setup) on a Mac with XQuartz, run it from a background command: ssh -Y -o ControlPath=none -o ControlMaster=no host '...; type module >/dev/null 2>&1 || source /etc/profile.d/modules.sh; module load <tool>; exec nice tool ...'. ControlPath=none matters. If an existing ControlMaster socket is reused, X11 forwarding may not be set up on that multiplexed session, or the GUI's long-lived channel may tie up a slot on a shared master. Non-interactive shells often lack the module function, so source modules.sh explicitly. Check that pgrep -x <toolproc> isn't already running first, so you don't take a second licence seat, and confirm DISPLAY=localhost:N.0 in the remote output.