Hello Mehdi,
Here is the JavaScript API that the Maps API wraps:
http://code.google.com/apis/maps/documentation/reference.html#GMarkerOptions
' This string will appear as tooltip on the marker, i.e. it
will work just as the
title attribute on HTML
elements. (Since 2.50)'
If you call MarkerOptions.setTitle("tooltip text"); the "tooltip text" string is just passed to set the 'title' property in the JavaScript API. That's all that gwt-google-apis currently does. If there is some trick to do something different, you'll probably find it by going to the Maps group. If you find a trick to do it in JavaScript and you can't do it in the GWT Maps API, please file it as an issue.
Thanks,
-Eric.
--
Eric Z. Ayers - GWT Team - Atlanta, GA USA
http://code.google.com/webtoolkit/