Speech Bubble Update (with Drop Shadow)

I added a drop shadow to the speech bubble. You don't need it on OSX (OSX provides one automatically), and I don't have compiz or similar compositing window manager installed on linux at the moment (although if anyone is willing to submit/test the corresponding code, I'm happy to include it).

Nothing fancy, just black with 50% alpha. The shadow mask is just the original mask, sheared, scaled, and offset. The drop shadow would probably look nicer with a blurred edge, but that likely requires a variable alpha setting for the window (although you might be able to fake it by varying the edge color). Applying per-pixel alpha masks prior to Windows Vista seems to be non-trivial (this example uses a single alpha value for the entire window).

The JNA function definitions are trivial:

    int GetWindowLongA(Pointer hWnd, int nIndex);
    int SetWindowLongA(Pointer hWnd, int nIndex, int dwNewLong);
    boolean SetLayeredWindowAttributes(Pointer hwnd, int crKey, 
                                       byte bAlpha, int dwFlags);

As is the actual usage:

    Pointer hWnd = getHWnd(w);
    User32 user = User32.INSTANCE;
    int flags = user.GetWindowLongA(hWnd, User32.GWL_EXSTYLE) | User32.WS_EX_LAYERED;
    user.SetWindowLongA(hWnd, User32.GWL_EXSTYLE, flags);
    user.SetLayeredWindowAttributes(hWnd, 0, (byte)(255*alpha), User32.LWA_ALPHA);

The only real trick is that DirectDraw must be disabled in order to get the transparency effect and avoid leaving behind painting artifacts.

java -Dsun.java2d.noddraw=true ...

NOTE: thanks to l2fprod for the hint and the original round, transparent clock!

Update: Demo is now available from the JNA homepage.