Adding a Window to a box blur

Hi,
i'm using davinci resolve (Free Version 15.1.0.025 on Windows 10) the first time. I want to create a sharpness progress using a box blur. But if i have selected the box blur, the window controls are greyed. So i cannot add a linear rectangle oder something like that. But i can user other tools like tracke, blur and so on. Do you have any idea about that circumstance?
Regards Martin
i'm using davinci resolve (Free Version 15.1.0.025 on Windows 10) the first time. I want to create a sharpness progress using a box blur. But if i have selected the box blur, the window controls are greyed. So i cannot add a linear rectangle oder something like that. But i can user other tools like tracke, blur and so on. Do you have any idea about that circumstance?
Regards Martin