what happens if your game is multi and one of the players loop stops when he dragged his window and this might cause some unwanted situations right??
The player who stopped their loop would stop moving and be completely open to attacks, and all the notifications of them taking damage that are sent from the server would be received rapidly after the loop continued again.
I am very experienced in multiplayer games and what happens when a player tries to stop the client - and when you make things server-side like you're supposed to, they find that they can't break the game by freezing their client.
People don't like it when your game doesn't have a windowed mode. You can decide whether you want it to be resized or not, and you can add an option for fullscreen (which should be off by default!), but whatever you do don't remove the window border. That will annoy people to no end.
There will always be at least one person who wants the game to be fullscreen. If possible, add the option for fullscreen, but it should be off by default because it's annoying when running a game for the first time it goes fullscreen and then you find out your computer can't handle it dropping the framerate so low you can't move the mouse to disable fullscreen.