Please help me with Interface Stuff

Your problem is the SDL_SetVideoMode function returns a pointer to that structure.

For some reason, this doesn't work (I get an unhandled memory exception in the catch):

Import "-lsdl"

Extern "C"

Type SDL_Surface

    Field flags:Int 
                     
    Field format:Byte Ptr 
    
    Field w:Int, h:Int 
    Field pitch:Short                 
    Field __unused_align_1:Short       
    Field pixels:Byte Ptr 
    Field offset:Int 
    Field hwdata:Byte Ptr 
             
    Field clip_rect_x:Short 
    Field clip_rect_y:Short 
    Field clip_rect_w:Short 
    Field clip_rect_h:Short 

    Field unused1:Int 
    Field locked:Int 
    Field map:Byte Ptr     
    Field format_version:Int 
    Field refcount:Int  
End Type


Function SDL_Init(Flags:Int)
Function SDL_SetVideoMode:SDL_Surface Ptr (Width:Int, Height:Int, Depth:Int, Flags:Int)
Function SDL_Flip(Screen:SDL_Surface Ptr)
Function SDL_FillRect(dst:SDL_Surface Ptr, dstrect:Byte Ptr, color:Int)
End Extern


Const SDL_INIT_VIDEO              = $00000020
Const SDL_HWSURFACE               = $00000001
Const SDL_DOUBLEBUF               = $40000000
Const SDL_FULLSCREEN              = $80000000



If SDL_Init(SDL_INIT_VIDEO)=-1
	End
EndIf

Print "Hello!"

Local ScreenSurface:SDL_Surface Ptr = SDL_SetVideoMode(800,600,32,SDL_HWSURFACE|SDL_DOUBLEBUF)
Try
	
	Print ScreenSurface[0].w
	Print ScreenSurface[0].h
	
Catch e : Object
	Print e.ToString();
End Try 

WaitKey

Repeat
	SDL_FillRect(ScreenSurface,Null,$FFFFFF)
	SDL_Flip(ScreenSurface)
	FlushMem()
Until KeyHit(KEY_ESCAPE)