I think you can solve it with a simple macro.
Check this one.
ActiveDocument.ShowPopup "This Macro display help text box", 2000,3,1,2
Hope it will help.
Display_Help_Box.qvw 144.2 K
You cannot make the help text as entered on the Caption tab appear on command. But you can create a new hidden text object (with a blue border and a light blue background, to mimic the help text pop-up) with a conditional show. Enter whatever help text you want to show in the Text field on the Properties->General tab.
The conditional show for that new text object will depend on the variable value as set by your original text box that carries a button image. For even better usability, create two question mark-buttons with different colors, one blue and one grey. The grey button will be displayed whenever the help text is visible, and the colored one when no help text is visible.