how to Install global mouse Hook for certain UI like "desktop"

Question

the code so far installs a hook to detect the mouse activity but what i want is either to filter the activity for certain UI or to detect where the clicks has occurred (on which hwnd ) exactly 'Desktop' is there a way ?

this is the code i've used it's from Microsoft website here : How to set a Windows hook in Visual C# .NET

EDIT : i found that he code provided by is not global so for global hook check link in the answer the answer ,,

Answer 1

First about the hook i found that it's not global and i found open-source global hook Here so whenever the mouse click occurs an event will fire and there i run simple callback code that checks if the desktop is the active control

[DllImport("user32.dll")]
static extern int GetForegroundWindow();

[DllImport("user32.dll")]
static extern int GetClassName(int hWnd, StringBuilder lpClassName, int nMaxCount);

public void GetActiveWindow() {
const int maxChars = 256;
int handle = 0;
StringBuilder className = new StringBuilder(maxChars);

handle = GetForegroundWindow();

if (GetClassName(handle, className, maxChars) > 0) {
    string cName = className.ToString();
    if (cName == "Progman" || cName == "WorkerW") {
        // desktop is active
    } else {
        // desktop is not active
    }
}

}

DONE!

special thanks to Micky Duncaand and AJKenny84