Monday, March 25, 2013

Enable Seamless Windows in XenApp 6.5 To Use Custom Window Color Scheme

After migrating an application from XenApp 5 on Windows Server 2003 to XenApp 6.5 on Windows Server 2008 R2, I got complaints from end users that the color scheme for their application on the new servers was hurting their eyes.

It turned out that the default grey color used by Server 2008 is lighter than in 2003, and it strained the eyes of the users and made it more difficult to see objects, such as text boxes, on the screen. After finding documentation on Citrix.com about a registry entry called SeamlessFlags, I added the value that is supposed to allow synchronizing of the system colors with the colors in the Citrix session, but it did not work. I actually found two separate Citrix KB articles with conflicting values. One said to use a hex value of 0x10 and another said 16 in decimal. Neither one worked.

I then downloaded a utility from Citrix called FarmTWIHelper, which is a GUI that helps configure the Seamless flag settings. I set the "Enable Color Sync" value, which added a value to the registry of 10 in hex and 16 in decimal, like I tried before. This still did not work.

I ended up playing with different settings and setting the decimal value to 10 (a in hex) finally worked, although I'm not sure why:

[HKEY_LOCAL_MACHINE\SYSTEM\CurrentControlSet\Control\Citrix\wfshell\TWI]
"SeamlessFlags"=dword:0000000a

Now I use a group policy to set the color values in HKEY_CURRENT_USER\Control Panel\Colors. The only problem I am still having is getting the custom colors to apply on a user's first logon. Currently, the user gets the default colors first, but the custom colors on all future logons.

References:
Seamless Configuration Settings
http://support.citrix.com/article/CTX101644

Case Study: Troubleshooting Seamless Flag - Custom Application
http://support.citrix.com/article/CTX127043

FarmTWIHelper - Seamless Configuration Helper Tool
http://support.citrix.com/article/CTX115146