No MouseHover event for Flat buttons on dialog redisplay

[jaxCtiDev]

My application is written in C# and has several dialog Windows Forms. All
button objects on all forms are using FlatStyle=Flat. I have background
colors on each button and tool-tips describing the use of each button. The
forms are all instantiated at start-up, but only the main form is displayed
(the other sub-forms need time to access resources on initial load, so they
are instantiated early, shown only when needed, and not destroyed and
re-instantiated). All tool-tips and button color-shade features on the main
form work fine all the time.

The problem is with the sub-forms. When shown for the first time, all
buttons and tool-tips work fine. However, once the form has been interacted
with and hidden (i.e. DialogResult=OK or Cancel) and then re-displayed later
for more interaction, the button tool-tips never again display and the button
colors stop changing as the mouse passes over. I tracked it down and have
found that the MouseHover event simply stops firing for sub-form buttons
after the first display-hide-display cycle.

This seems to be a system bug. Has anyone seen this besides me? Is there a
work-around or patch (short of having to destroy and re-create each form as
it is needed)?

Thanks in advance.