Hy Dmitry!

>Is it possible to have a message displayed when mouse is over a textbox, but without using ToolTipText?
>Thank you.

What kind of message?

You can try to put some code in MouseMove like these:

Messagebox("My message")
* Or
Wait Window "My message"
* Or
Set Message To "My message"   && Display message in StatusBar 
                              && See in help: Set Message To or
                              &&              StatusBarText property

I hope this help you.
Bye!