this is apples app restore in effect
it reopens windows that were open when you quit the app
let me dig up some code to check for it and then in app.open you close it and no issue
add this method somewhere and call it in the app.open event
Sub CloseNSColorPanel
#If TargetMacOS Then
Declare Function NSClassFromString Lib "AppKit" ( className As CFStringRef ) As ptr
Declare Function sharedColorPanel Lib "AppKit" selector "sharedColorPanel" ( classRef As Ptr ) As Ptr
Declare Sub close Lib "AppKit" selector "close" ( panel As Ptr )
close( sharedColorPanel( NSClassFromString( "NSColorPanel" ) ) )
#endif
end sub
that should do it