Computer Configuration > Administrative Templates > Citrix Components > Citrix Workspace > SelfService
Machine
HKLM\SOFTWARE\Policies\Citrix\Dazzle
Use this option to change the default FTA (File Type Association) settings. By default, this policy is set to Not Configured. Select Enabled to enable the default FTA. Select Disabled to disable the default FTA. When the 'Enable FTA' is disabled, setting this policy will take no effect. The policy will be treated as disabled.