FZ: warn w/ a toast if an elevated window cannot be dragged and offer learning more

src/common/window_helpers.cpp

@@ -1,5 +1,7 @@
 #include "window_helpers.h"
 #include "pch.h"
+#include <wil/Resource.h>
+
 
 HWND CreateMsgWindow(_In_ HINSTANCE hInst, _In_ WNDPROC pfnWndProc, _In_ void* p)
 {
@@ -27,4 +29,32 @@ HWND CreateMsgWindow(_In_ HINSTANCE hInst, _In_ WNDPROC pfnWndProc, _In_ void* p
     }
 
     return hwnd;
-}
+}
+
+bool IsProcessOfWindowElevated(HWND window)
+{
+    DWORD pid = 0;
+    GetWindowThreadProcessId(window, &pid);
+    if (!pid)
+    {
+        return false;
+    }
+
+    wil::unique_handle hProcess{ OpenProcess(PROCESS_QUERY_LIMITED_INFORMATION,
+                                             FALSE,
+                                             pid) };
+
+    wil::unique_handle token;
+    bool elevated = false;
+
+    if (OpenProcessToken(hProcess.get(), TOKEN_QUERY, &token))
+    {
+        TOKEN_ELEVATION elevation;
+        DWORD size;
+        if (GetTokenInformation(token.get(), TokenElevation, &elevation, sizeof(elevation), &size))
+        {
+            return elevation.TokenIsElevated != 0;
+        }
+    }
+    return false;
+}