enable/disable clickthrough


New member
Aug 4, 2017
Programming Experience
I'm making a game overlay in Unity and have a question.

The people on the forum there pointed me in this directions since its Windows related and not directly related to Unity.

I found the code (found below) to make my screen transparent and clickthrough.
But I want the clickthrough function to be disabled when the mouse is over a object of my overlay so it can be receive a mouse click.
My object detects the mouse over, but not the click. So in the "mouse enter (over) event" I would need to put a code to reverse the click through and re-apply it when "mouse exit (not over) event" is called.

Now i will be honest and say that I dont understand the code displayed below. but it does what I need. But I can not figure out what produces the clickthrough and how to toggle it on and off without affecting the tranparency.

Could anybody give me a hand please?

using System;
using System.Runtime.InteropServices;
using UnityEngine;

public class TransparentWindow : MonoBehaviour
    private Material m_Material;

    private struct MARGINS
        public int cxLeftWidth;
        public int cxRightWidth;
        public int cyTopHeight;
        public int cyBottomHeight;

    private static extern IntPtr GetActiveWindow();

    private static extern int SetWindowLong(IntPtr hWnd, int nIndex, uint dwNewLong);

    static extern bool ShowWindowAsync(IntPtr hWnd, int nCmdShow);

    [DllImport("user32.dll", EntryPoint = "SetLayeredWindowAttributes")]
    static extern int SetLayeredWindowAttributes(IntPtr hwnd, int crKey, byte bAlpha, int dwFlags);

    [DllImport("user32.dll", EntryPoint = "SetWindowPos")]
    private static extern int SetWindowPos(IntPtr hwnd, int hwndInsertAfter, int x, int y, int cx, int cy, int uFlags);

    private static extern uint DwmExtendFrameIntoClientArea(IntPtr hWnd, ref MARGINS margins);

    const int GWL_STYLE = -16;
    const uint WS_POPUP = 0x80000000;
    const uint WS_VISIBLE = 0x10000000;
    const int HWND_TOPMOST = -1;

    void Start()
#if !UNITY_EDITOR // You really don't want to enable this in the editor..

int fWidth = Screen.width;
int fHeight = Screen.height;
var margins = new MARGINS() { cxLeftWidth = -1 };
var hwnd = GetActiveWindow();

SetWindowLong(hwnd, GWL_STYLE, WS_POPUP | WS_VISIBLE);

// Transparent windows with click through
SetWindowLong(hwnd, -20, 524288 | 32);//GWL_EXSTYLE=-20; WS_EX_LAYERED=524288=&h80000, WS_EX_TRANSPARENT=32=0x00000020L
SetLayeredWindowAttributes(hwnd, 0, 255, 2);// Transparency=51=20%, LWA_ALPHA=2
SetWindowPos(hwnd, HWND_TOPMOST, 0, 0, fWidth, fHeight, 32 | 64); //SWP_FRAMECHANGED = 0x0020 (32); //SWP_SHOWWINDOW = 0x0040 (64)
DwmExtendFrameIntoClientArea(hwnd, ref margins);


    void OnRenderImage(RenderTexture from, RenderTexture to)
        Graphics.Blit(from, to, m_Material);
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