This is actually a bug report about Wubi which is a software project that allows you to install Ubuntu - not Ubuntu itself. Subsequently, I've opened a Wubi task and closed the Ubuntu one.
The tooltip is a fairly standard windows tooltip, and the size depends on the text contained. You might want to suggest some replacement text. To make it smaller we would need to remove the description of the contained distros, but I think that a bit of explanation is in order since most users will have no clue about Kbuntu or Xubuntu .
can not u change them to the same color that tooltips have in windows (yellow)