c# Create a windows borderless application for different applications

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C#

.NET

Hey guys, I'm new to code project but I couldn't find anything on here. so here it is. I would like to create an application for making a windowed screen borderless and fullscreen. I like playing in windowed mode for easy alt tabbing etc. So I would like to find out what I can learn to achieve this.

The reason I would like to know is because I know it is possible:
this is the code to do it for black ops in AHK, But I don't want to do it in AHK, I want to do it in my own application with my own UI and do some learning on the way.

width = 1680
height = 1010

ifexist %A_AppData%\BlackOps Windowed Borderless Mode\settings.ini
{
IniRead, width, %A_AppData%\BlackOps Windowed Borderless Mode\settings.ini,Settings,Width
IniRead, height, %A_AppData%\BlackOps Windowed Borderless Mode\settings.ini,Settings,Height
}

Start:
gui +alwaysontop
gui font, s10
gui add, text, section x15 y15, Width:
gui add, edit, ys-2 w50 vWIDTH, %width%
gui add, text, x+20 ys, Height:
gui add, edit, ys-2 w50 vHEIGHT, %height%
gui font, s12
gui add, button, xs y+15 h30 default, Set BlackOps to Borderless
gui font, s7
gui add, checkbox, y+15 vSave Checked, Save settings
gui font, s7 cGray
gui add, text,, writes to an ini file to:`n%A_AppData%\BlackOps Windowed Borderless Mode\
gui show, ,BlackOps Borderless Windowed Tool by piXelman, modified by Scarystuff
Return

ButtonSetBlackOpstoBorderless:
Gui Submit
Gui Destroy

if (width = "" or height = "") {
msgbox 48, BlackOps Borderless Windowed Mode, Width/Height must not be blank!
Goto Start
}

if (save = 1) {
ifnotexist %A_AppData%\BlackOps Windowed Borderless Mode
FileCreateDir %A_AppData%\BlackOps Windowed Borderless Mode

IniWrite, %width%, %A_AppData%\BlackOps Windowed Borderless Mode\settings.ini,Settings,Width
IniWrite, %height%, %A_AppData%\BlackOps Windowed Borderless Mode\settings.ini,Settings,Height
}


IfWinExist Call of Duty®: BlackOps ; find BlackOps if it is running
{
WinActivate Call of Duty®: BlackOps ;activate the window
WinMove,Call of Duty®: BlackOps,,0,0,1680,1010 ; resize it to 1600x1024 (modify to match resolution set in BlackOps config)
WinSet Style, -0x800000 ;fix border
WinSet Style, -0xC00000 ;noborder
ExitApp
} else {
MsgBox 5,BlackOps Borderless Windowed Mode, Call of Duty®: BlackOps is not running! Start it up and hit Retry
IfMsgBox Retry
Goto Start
ExitApp
} 

That includes a GUI and stuff.

But yeah, IDK if that code helps with anything but.

Main point:: Does anyone know how to make an application (like black ops) go to fullscreen borderless, when in windowed. using c# pref. but vb or c++ are fine (I know sh*t all c++ though)

Cheers for any help!! :D