How to make Visio viewer work on IE9

Description

I had trouble getting the Visio viewer control to work on IE9 (including FireFox IE tab and Chrome IE tab). It seems that no matter what my IE security options were set at, the control would not automatically download.

Steps

This is what worked for me on Windows 7:

1. Go to the Microsoft Visio Viewer download site and install the viewer directly
2. Restart IE (important!)
3. Test on IE with the Visio viewer test (not dependent on the Visio for Confluence). If it works here, then it should also work in Confluence. And once working with IE, should also work in FireFox IE tab and Chrome IE tab. 

References

Google: visio activex IE9, or similar, to find a few references about the things that need to be done like making sure ActiveX filtering is off, and making a file association for .vsd files with IE. These things didn't seem to make a difference for me. In particular, with the steps above, you do not need to touch the activeX filtering option.