1) Thunderbird and Pale Moon made from Mozilla engine. Similar to Firefox. Which I know have some compatibility issue with Windowblinds and one of it is the missing title text. As of today latest version of Firefox still not fully compatible with Windowblinds. This might be because they have their own skinning engine build into them.
Update: I can confirm the text in the titlebar appears when the windows are maximized or a caption button is in its "hot" (moused over) state. I don't really think it's an issue of these programs using their own skinning engines because if that were the case, they wouldn't have the support they do, right?
Also, I don't know if it's relevant, but Pale Moon is based off of Firefox 38, which had a different behavior in regards to theming than current versions of Firefox do. I'm using Thunderbird 52, which I'm pretty sure also themes better than current versions. But both Pale Moon and Thunderbird 52 work fine with both Windows and Windowblinds themes under Windows 7.
Any ideas for how to fix this issue? Is there something I can do on my end? Thanks.