The screen might not repaint properly because of a poor refresh rate. Therefore, certain areas of the application appear grayed out or distorted. This happens when running an application in seamless mode while utilizing the pass-through client on the server.

• Manually refreshing the application does not help.

• Running the same application in a fixed window size, rather than seamlessly, does not produce the preceding symptom.

• Running the application seamlessly, without utilizing the pass-through client, does not produce the preceding symptom.

Complete the following steps to resolve the issue:

1. ​Add the following two values to the [wfclient] section of the Appsrv.ini file located in the C:\Program Files (x86)\Citrix\ICA Client" or "C:\Program Files (x86)\Citrix\Online Plugin directory:
   ForceLVBMode=1
   DeferredUpdateMode=True

2. Add the following two registry entries under:
   HKEY_LOCAL_MACHINE\SOFTWARE\Citrix\ICA Client\Engine\Configuration\Advanced\Modules\WFClient
   
   Name: ForceLVBMode
   Type: REG_SZ
   Data: 1
   
   Name: DeferredUpdateMode
   Type: REG_SZ
   Data: True

   For 64bit, use: 
   HKEY_LOCAL_MACHINE\SOFTWARE\Wow6432Node\Citrix\ICA Client\Engine\Configuration\Advanced\Modules\WFClient
   
   Name: ForceLVBMode
   Type: REG_SZ
   Data: 1 (default setting is 0)
   
   Name: DeferredUpdateMode
   Type: REG_SZ
   Data: True

This issue can also be resolved by the following:

• If ICA files are being used to access an application, the same two values added to the Appsrv.ini file must also be included in the ICA file.

• Disable client info sync, refer to CTX101644 – Seamless Configuration Settings.

CTX136671 - Frequently Overlooked Settings to Improve Graphics Performance for XenApp, XenDesktop, Receiver Technologies