Android emulator in Windows 10 has no border
This isn't normally a Windows-centric area, and generally questions about emulators would fall into the programming off-topic arena. You can probably bring the emulator to the forefront in Windows 10 by the following KEYBOARD entries (and you should know them anyway by heart). The System Menu which, appears at the top-left of windows, can be accessed even WITHOUT A MOUSE! You can move windows into the current viewport with the keyboard + careful arrow usage.


Activate the specific window you want to move - you may be able to click with the mouse.
KEYBOARD entry to activate the System Menu: Alt + Spacebar
KEYBOARD entry to activate the MOVE command: Down-arrow + Enter
KEYBOARD entry to move the window to your liking: Arrows: Left,Right,Up,Down until you can see the menubar(s) you need.
KEYBOARD entry to leave the window in position: Enter
Continue with mouse, menus, etc. to find command related to positioning the window size permanently.