Issue with windowed mode

I decided to play in windowed mode because I am glad for every fps boost I can get. But i noticed that some things are strangely blured- it looks like the width is okay but the height of my GMod screen is reduced, because I can see small white bars on top and bottom of my screen, although I haven’t changed the resolution from native (1366x768). I can see the blur mostly on text in console and tool menu. I already disabled Aero snapping so I will see the game window more fullscreenish, but still I can’t move it fully to the top part of the screen because it moves back by few pixels. It could be causing the window height reduce.

My laptop is Acer Aspire 5349 with Windows 7 Home 64bit. The only startup command I have is -sw because my video settings are getting reverted back to recommended and my text disappears when I switch from window to fullscreen or back, ingame.

EDIT: I just found that the Windows 7 is making the windows rearranging even after the snapping is disabled. When you move a non-maximized window beyond the the top edge of the screen while touching the bottom of it’s top panel so you will only see a thin stripe on the top of your screen, the window moves down a little bit and also shortens it’s height, making the GMod’s sharp displaying screwing up and bluring it. Is it possible to disable this?

Add the following command line options(if you don’t have these):

to get borderless window. To set it’s size you’ll need to add these command line options right next to existing ones:

This should force Garry’s Mod to use borderless window with specified size.
To get every command line option for both GoldSrc and Source engines go here: https://developer.valvesoftware.com/wiki/Command_Line_Options