>Is there a way to display ToolTipText on demand? For example by firing GotFocus() event of TextBox with ToolTipText set.

This idea seems rather simplistic, but you could add something like this to your GotFocus()

WAIT This.ToolTipText WINDOW AT nRow, NCol NOWAIT 

Calculate nRow and nCol based on the Top and Left of the object. This works as long as you don't mind it not looking like a tool tip. Of course you could could get fancy and define a window that looks more like a tool tip, but before you go to all that trouble, you should look for a tool tip control in the download section.