WPF and regular Win32 windows are now supported

Added support for dragging target on WPF windows and building simple
xpath statements.  Fixed some null results in native library and
increased performance of enumerating wpf windows.  Still need to tweak
filters for picking up Silverlight handles too.

src/org/synthuse/WinPtr.java

@@ -0,0 +1,52 @@
+package org.synthuse;
+
+import com.sun.jna.platform.win32.WinDef.HWND;
+
+public class WinPtr {
+
+	public HWND hWnd = null;
+	public String hWndStr = "";
+	public String runtimeId = "";
+	
+	public WinPtr() {
+	}
+	
+	public WinPtr(HWND hWnd) {
+		this.hWnd = hWnd;
+		this.hWndStr = Api.GetHandleAsString(hWnd);
+	}
+
+	public WinPtr(String runtimeId) {
+		this.runtimeId = runtimeId;
+	}
+	
+	public boolean isWin32() {
+		return (hWnd != null || !hWndStr.equals(""));
+	}
+	
+	public boolean isWpf() {
+		return (!runtimeId.equals(""));
+	}
+	
+	public boolean isEmpty() {
+		return (hWnd == null && hWndStr.equals("") && runtimeId.equals(""));
+	}
+	
+	public static boolean isWpfRuntimeIdFormat(String runtimeIdTest) {
+		return (runtimeIdTest.contains("-"));
+	}
+	
+	public String toString() {
+		if (isWin32() && !hWndStr.equals(""))
+			return hWndStr;
+		else if (isWin32() && hWnd != null)
+		{
+			hWndStr = Api.GetHandleAsString(hWnd);
+			return hWndStr;
+		}
+		else if (isWpf())
+			return runtimeId;
+		else
+			return null;
+	}
+}