Edit: I moved the original question to 'The docked gVim in Windows 7 jumps upon tab switch'
After struggling with my .vimrc, I am resorting to setting the font from windows registry instead, because without the guifont in .vimrc, everything works fine. The only registry mentioned I found was,
HKLM\Software\Microsoft\WindowsNT\CurrentVersion\Console\TrueTypeFont
This is for MS command line, but it was not what I was looking for. Currently gVim is set to Fixedsys by default. The search though the registry for value fixedsys returned no result. My gut feeling is that one can change it through the registry setting. Is there such registry value?