Before installing the Citrix Online plug-in, File Type Associations for certain types of locally installed applications such as Microsoft Office are directed to launch the content files using the locally installed applications. After installing the Program Neighborhood Agent component, the File Type Associations are updated to specify the Citrix Online plug-in.
Set File Type Associations might look like this:

From the Online Plug-in version12.0 for Windows, we have a setting to specify whether to use local File Type Associations or the ones created by Program Neighborhood Agent used to redirect files to be opened on the XenApp server.

Create a Registry Key:
HKCUSoftwareCitrixPNAgent FavorLocalApps = 0 (REG_DWORD)

This solution is valid only for Receiver versions 3.x or earlier.