Comment 3 for bug 427888

I also just recognized the following:

when changing the midi player command, and then cancelling the preferences dialog, there no warning shows up.

adding the following to Sound.tcl to proc ::Sounds::CancelPrefsHook will create a warning when midiplayer was changed an cancel pressed:

    if {![string equal $sprefs(midiCmd) $tmpPrefs(midiCmd)]} {
        ::Preferences::HasChanged
    }