GUI N64 vibration test only works intermitently (CLI works fine)

[LukeShu]

The gcn64ctl_gui "Test vibration" button only sometimes causes my N64 controller to start vibrating, and when it does start then the "Stop vibration" button only sometimes causes it to stop vibrating. With gcn64ctl the --n64_control_rumble flag works consistently.

This is with

• a Gamecube/N64 to USB adapter v3.6 (ADAP-GCN64-USB_V3) (p/n: 6-070)
• Firmware 3.6.1
• GNU/Linux
• gcn64tools 2.1.25
• an N64 controller with Rumble Pak