ClearType (aka Font Smoothing) is a software technology developed by Microsoft that improves the readability of text on existing LCDs, such as laptop screens, Pocket PC screens and flat panel monitors. With ClearType font technology, the words on your computer screen look almost as sharp and clear as those printed on a piece of paper.

For the longest time Microsoft ClearType has been working properly inside an ICA session with Citrix Presentation Server running on Windows 2000 Server, but it did not work with XenApp 4.5 running on Windows Server 2003.

As previously mentioned Citrix was working on an update to XenApp 4.5 for Windows Server 2003 to utilize this new Microsoft Update for Terminal Services to provide ICA users with ClearType support.

Well, on July 7th (yesterday) Citrix released a hotfix for XenApp 4.5 on Windows Server 2003 that enables ClearType on its XenApp 4.5 Servers.

Steps to enable ClearType on your Citrix XenApp Server:

Make sure you have
1) Citrix XenApp 4.5 with Rollup Pack 02 installed
2) Windows Server 2003 SP1 with KB946633 installed

Then
3) Download and Install Hotfix CTX117434

Note: This patch also rectifies several other issues in XenApp 4.5. You can find the list of fixes by clicking here.

If you want to learn more about ClearType, I can suggest two great articles on this subject:

Cheers,
Gus