FVWM: In "Style" command , how to find the application name, mplayer or MPlayer or gmplayer?

[for.register for.register]

Hi,

Style MPlayer       !Title,  !Borders
Style Conky           !Title,  !Borders
Style feh                 !Title,  !Borders

the above config works,

but the following don't work

Style gmplayer       !Title,  !Borders
Style conky           !Title,  !Borders
Style Feh                 !Title,  !Borders

so, my question is how to find the exact name in the above config?