Dont trigger if modifier key is down

README.md

@@ -67,4 +67,7 @@ Tavis Ormandy [@taviso](https://github.com/taviso/)
 
 
 * Q: How do I turn it off without rebooting?
-* A: Use [Process Explorer](https://technet.microsoft.com/en-us/sysinternals/processexplorer.aspx), [Process Hacker](http://processhacker.sourceforge.net/), [Task Manager](https://en.wikipedia.org/wiki/Task_Manager_\(Windows\)), or [taskkill.exe](https://technet.microsoft.com/en-us/library/bb491009.aspx) to Suspend or Terminate the process. I told you it was minimal!
+* A: Use [Process Explorer](https://technet.microsoft.com/en-us/sysinternals/processexplorer.aspx), [Process Hacker](http://processhacker.sourceforge.net/), [Task Manager](https://en.wikipedia.org/wiki/Task_Manager_\(Windows\)), or [taskkill.exe](https://technet.microsoft.com/en-us/library/bb491009.aspx) to Suspend or Terminate the process. I told you it was minimal! It also doesn't do anything if you're holding Shift, Control, Alt, etc.
+
+* Q: Why doesn't it work if my current program is running as an Administrator?
+* A: [UIPI](https://en.wikipedia.org/wiki/User_Interface_Privilege_Isolation). I suppose you could "Run As Administrator" if it bothers you.

hotcorner.c

@@ -5,24 +5,8 @@
 #pragma comment(lib, "USER32")
 #pragma comment(linker, "/SUBSYSTEM:WINDOWS")
 
-// In GNOME 3 whenever you move the mouse to the top left corner, GNOME
-// switches to the activities view, it looks like this:
-//
-//  https://www.gnome.org/wp-content/uploads/2016/03/window-selection-3.20-420x236.png
-//
-// Whenever I'm using Windows, I always forget that this doesn't work. Bleh.
-//
-// I searched around for existing solutions, and wasn't happy with anything I could find.
-//
-// The options seem to be
-//
-//  * Some ridiculous AutoHotKey/AutoIT monstrosity (?!?).
-//  * Massive Delphi application with 100MB of resources.
-//  * Some naive program that polls GetCursorPos() in a busy loop.
-//
-// None of these are what I want, I just want that GNOME 3 thing with absolute
-// minimal overhead.
-// 
+#define KEYDOWN(k) ((k) & 0x80)
+
 // This is a **very** minimal hotcorner app, written in C. Maybe its not the
 // optimal way to do this, but it works for me.
 //
@@ -61,10 +45,28 @@ static HANDLE CornerThread = INVALID_HANDLE_VALUE;
 // If the mouse leaves while we're waiting, the thread is just terminated.
 static DWORD WINAPI CornerHotFunc(LPVOID lpParameter)
 {
+    BYTE KeyState[256];
     POINT Point;
 
     Sleep(kHotDelay);
+
+    // Check if a mouse putton is pressed, maybe a drag operation?
+    if (GetKeyState(VK_LBUTTON) < 0 || GetKeyState(VK_RBUTTON) < 0 || GetKeyState(VK_MBUTTON < 0)) {
+        return 0;
+    }
 
+    // Check if any key is pressed.
+    if (GetKeyboardState(KeyState) == FALSE) {
+        return 1;
+    }
+
+    // Check if any modifier keys are pressed.
+    if (KEYDOWN(KeyState[VK_SHIFT]) || KEYDOWN(KeyState[VK_CONTROL])
+     || KEYDOWN(KeyState[VK_MENU]) || KEYDOWN(KeyState[VK_LWIN])
+     || KEYDOWN(KeyState[VK_RWIN])) {
+        return 0;
+    }
+
     // Verify the corner is still hot
     if (GetCursorPos(&Point) == FALSE) {
         return 1;