AdvSplash.dll - small (5.5k), simple plugin that lets you throw 
up a splash screen in NSIS installers with cool fading effects (win2k/xp)
and transparency.

To use:

Create a .BMP file of your splash screen.
(optional) Create a .WAV file to play while your splash screen shows.

Add the following lines to your .NSI file:

Function .onInit
  SetOutPath $TEMP
  File /oname=spltmp.bmp "my_splash.bmp"

; optional
; File /oname=spltmp.wav "my_splashshit.wav"

  advsplash::show 1000 600 400 -1 $TEMP\spltmp

  Pop $0 ; $0 has '1' if the user closed the splash screen early,
         ; '0' if everything closed normally, and '-1' if some error occurred.

  Delete $TEMP\spltmp.bmp
;  Delete $TEMP\spltmp.wav
FunctionEnd

Calling format
        advsplash::show Delay FadeIn FadeOut KeyColor FileName

Delay - length to show the screen for (in milliseconds)
FadeIn - length to show the fadein scene (in ms) (not included in Delay)
FadeOut - length to show the fadeout scene (in ms) (not included in Delay)
KeyColor - color used for transparency, could be any RGB value 
        (for ex. R=255 G=100 B=16 -> KeyColor=0xFF6410), 
        use KeyColor=-1 if there is no transparent color at your image.
FileName - splash bitmap filename (without the .bmp). The BMP file used will be 
        this parameter.bmp, and the wave file used (if present) will be this 
        parameter.wav.

(If you already have an .onInit function, put that in it)

Note 1: fadein/fadeout supported only on win2k/winxp systems, all other systems
will show simple splash screen with Delay = Delay + FadeIn + FadeOut. Also, I've
noted my winXP uses no transparent color at 16 bpp, so at bpps lower than 32
for images with transparent color no fading effect will occur.

Note 2: the return value of splash is 1 if the user closed the splash 
screen early (pop it from the stack)

-Justin
Converted to a plugin DLL by Amir Szekely (kichik)
Fading and transparency by Nik Medved (brainsucker)