How To Keep A Form On Top Of Others In VB.NET?

I'm working on a application that has a main form and a floating form that contains some useful tools. I want it to be on top of my main form. so I tried ToolForm.TopMost = True but when i go to another application it is still on top. how can I implement it in my app? being the top most just forms of the application.

Something Like Find And Replace Window in Visual Studio