Seamless mode:

Applications delivered by XenApp and XenDesktop without a desktop are referred as seamless applications. Seamless mode allows remote applications to appear as though they are installed locally i.e., applications appear integrated with local operating system. Seamless applications gives look and feel like applications are installed locally. Without seamless applications, all applications are shown in a Citrix window. Users can maximize and minimize these seamless applications.

Wfshell.exe is the shell that responsible for controlling seamless application delivery which runs on virtual delivery agent, in same session as user’s remote applications.

Sometimes, we might end up in issues like a minimized seamless application doesn’t maximize. Or some dropdowns or keys doesn’t work in seamless application. Use hotkey shift + F2 hotkey on end point device to disable seamless view and to enable Citrix window. This will show the application in a window. By using this way, we can identify if the issue is with seamless setting. We can go ahead and change the seamless setting from registry, if it is causing the problem.

Checkout this link for seamless settings: https://support.citrix.com/content/dam/supportWS/kA460000000Cc9BCAS/Seamless_Configuration.pdf

You can also configure seamless settings using a citrix tool given here: https://support.citrix.com/article/CTX222592