Yeah, it looks like you're running Chrome in full screen mode. Hold on a second.... I just opened Chrome to make sure and yes, that's what you're doing.
Move your cursor toward the top of the screen until the top menu appears. Click on the blue opposing arrows to reduce Chrome back to regular screen size. Once there, adjust Chrome so that it's smaller in width and length. And don't run it full screen.
Is that a single finder window or is it a drop down from another App you select your file then open or cancel ??
If its the later, then i has to do with that particular App UI and there is not much you can do about it.
if its just a single finder window goto a corner and hover the cursor over it then click and drag to resize.
You could even try this if it is the drop down too but i don't think it will work ……. Cant hurt
Cheers
EDIT : Looks like Charlie picked it
Welcome . . .Thanks so much!!! That worked. I was trying to open a file in Chrome and I was able to resize the file selection window by clicking a dragging the border to resize the window.