I tried it, and it seems to only move when the screen has changed in dimensions equal to the width of the minimap.
EG: The minimap is x pixels wide. The minimap doesn't move if I resize the window, except when it is a multiple of x pixels, and then the minimap snaps to the edge of the screen. This also doesn't stay correctly positioned, as when I hit play, the other elements don't line up if it's not a multiple of x pixels wide.
Here's my setup.
In the hierarchy picture, "Panel" is my single UI panel for clipping reasons. Then, I have the invisible widget (name as TopRight) as a child of that, anchored to the top right corner of "Panel", with my other widgets as children of the invisible widget, position at the corner of the screen.
Then, if I resize my window it doesn't move until it is x (the width of the minimap sprite) pixels smaller, the minimap snaps to the corner where it's supposed to be anchored.
How can I make it constantly move with the corner and stay anchored? :/
I also noticed that when positioning, I couldn't drag it nicely where I wanted, and it would "snap" around as if to a grid, and not free floating. I had to enter decimals to position the minimap widgets.