UpDate! This only works when windowblinds is off and one is using windows 7 themes, I thought I found the a fix, but i was mistaken, sorry.
I upgraded to the new versions of Windows 7 and WindowBlinds 7.01, and Yahoo Instanst Messenger 10, and after all the new upgrade were installed I notice that yahoo messenger 10 was not skinned by WindowBlinds 7.
In older versions of yahooo messenge all one had to do to cause yahoo to be skinned by windowblinds was to click on messenger on the yahoo interface and then click preferences, and then select the classic skin to allow yahoo to be skinned by window blinds, but in the new yahoo messenger 10 there is no place to choose the classic skin.
So all i did was, go to start menu, then to programs, then to my yahoo folder, then I right moused clicked the yahoo icon, and then I clicked on compatablity tab, and then I checked the box next to disable visual theme, and then apply, and that cause my yahoo messener version 10s interface to be skinned by windowblinds 7.
I hope this helps other yahoo messenger 10 users.