Indeed, adjusting proper window dimensions, fixed my missing pixel problem. Thanks C0lumbo. Flickering textures to be solved
Ahaa, I was able to solve flickering texture. Turns out, whenever I set camera coordinates according to character position, x and y coordinate were not rounded ( -10.5645;45.4545, for example ) and that resulted, I guess, in awkward camera placement or something. Anyway, coordinate rounding solved it. Thanks.