getEnabled

This Callback sets a boolean value to define whether a control is displayed as active or inactive.

Sample Ribbon XML file:

<customUI xmlns="http://schemas.microsoft.com/office/2006/01/customui" onLoad="CallbackOnLoad">
    <ribbon startFromScratch="false">
         <tabs>
             <tab id="Toogle Button Demo" label="Toogle Button Demo">
                <group id="MyGroup" label="Toogle Button Demo">
                    <button id="MyButton" label="I ;-)"
                      image="myImageEN.JPG" 
                      size="large" getEnabled="CallbackGetEnabled"/> 
                    <toggleButton id="MyToggleButton1" size="large" 
                      label="Toggle Button (On/Off)" imageMso="HappyFace"
                      onAction="MyToggleButtonCallbackOnAction"/>
                </group>
            </tab>
        </tabs>
    </ribbon>
</customUI> 

Function to be copied to a standard module: 

Option Compare Database
Option Explicit
  
Public bolEnabled As Boolean
  
Sub CallbackGetEnabled(control As IRibbonControl, _
                       ByRef enabled)
' Callback Enabled
    enabled = bolEnabled
End Sub 

Furthermore you require the Callback for clicking the ToggleButton

You can find this sample in Sample DB 2