%bh (Bubble Help) takes an INTEGER argument that is a control variable. When this variable is non-zero, help text is supplied in the form of a "bubble" whenever the mouse cursor lies over the control in question. To enable users to switch such help on and off, simply supply a button with a call-back function that changes the integer control variable.
hlp='Toggle bubble help On/Off'
c--- Define a button with help attach the help ---
c--- string with an @ symbol ---
INTEGER FUNCTION toggle()
A grave accent can be added to %bh. This has the effect of generating a short delay before the help bubble appears.
%th (Tooltip Help) is used as an alternative to %`bh. %th provides a help bubble in the form of a "tooltip".