property MsgBox.Button(Button as OutResult) as String
Specifies the caption for the specified button.

TypeDescription
Button as OutResult An OutResult expression that indicates the identifier of the button being changed. 
String A string expression that indicates the new button caption.
Use the Button property to assign a new caption for standard buttons. The Button has effect for the next call of the Out method. Use the Image property to assign new images for exInformation, exQuestion, exCritical or exExclamation predefined types.

The Button property accepts HTML format like follows:

The following sample changes the color for Abort button:

With MsgBox1
    .Button(exAbort) = "<fgcolor=FF0000>Abort</fgcolor>"
    .Out "This is the message box's prompt", OutStyle.exAbortRetryIgnore
End With