You can change the icon and put the text in there, AFAIK, there is no way to use a regular text

As far as I can tell, Timo is correct, as the control loads as an asp image button:
 

VISIBILITY.ASCX
<asp:LinkButton ID="cmdVisibility" Runat="server" CausesValidation="False">
<asp:Image ID="imgVisibility" Runat="server"></asp:Image>
</asp:LinkButton>

You would need to use a custom image in your container like this:

<dnn:VISIBILITY runat="server" id="dnnVISIBILITY" minicon="ico_max.gif" maxicon="ico_min.gif" />

Or, like Sebastian says, create a custom control.

Jon

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