    Window calls

Note: X is the horizontal axis and Y is the vertical axis.
 
Insert SCR instruction after setting the registers to make a window call.

  New window (AX == 0)
  
BX = horizontal resolution
CX = vertical resolution
DX = pointer to a string containing window title
EX = keypress interrupt signal
FX = port to read keypresses
GX = (optional) signal that is given to the program when the window is clicked
     using mouse
HX = (optional) starting port that is used to read mouse position

Creates a new window. Window descriptor is returned in AX.
If GX is not zero, port in HX contains mouse cursor's X position and port HX+1
contains Y position.


  New fullscreen window (AX == 1)
  
BX = Display mode
DX = pointer to a string containing window title
EX = keypress interrupt signal
FX = port to read keypresses
GX = (optional) signal that is given to the program when the window is clicked
     using mouse

Creates a fullscreen window. Supported display modes are 0x06, 0x0F, 0x10,
0x11, 0x12 and 0x13. A double buffer is allocated if enough memory is
available. Window contents are then drawn into the double buffer and must be
updated to display memory using the update call (AX == 2).


  Draw pixel (AX == 5)
  
EX = Window descriptor
BX = X
CX = Y
DX = Pixel color

Draws pixel to position X,Y in window.


  Video memset (AX == 6)
  
BX = starting point's X
CX = starting point's Y
DX = color
EX = window descriptor
FX = count

Sets FX pixels in window to color DX. The row is incremented when the right
border of the window is reached.


  Video memcpy (AX == 7)
  
BX = starting point's X
CX = starting point's Y
DX = pointer to buffer
EX = window descriptor
FX = count

Copies FX bytes from buffer in DX to window. One byte in the buffer
corresponds to one pixel.


  Update (AX == 2)
  
EX = Window descriptor

Updates window contents.


  Clear (AX == 3)

EX = Window descriptor
  
Removes any individually drawn pixels from the window.


  Text (AX == 4)
  
BX = X
CX = Y
DX = Pointer to text
EX = Window descriptor
FX = text color

Writes text to a window. Returns -1 into AX if error, otherwise the register
contents are unmodified.


  Button (AX == 8)
  
BX = X
CX = Y
DX = Pointer to text
EX = Window descriptor
FX = Text color
GX = Width
HX = Height

Inserts a button to a window. Returns the keycode of the button into AX
register.


  Textbox (AX == 9)
  
BX = X
CX = Y
DX = Pointer to text
EX = Window descriptor
FX = Max length of string
GX = Width in pixels

Inserts a textbox to a window. Returns the keycode of the element into AX and
element descriptor into BX.


  Multi-line list (AX == 10)
  Multi-line textbox (AX == 16)
  
BX = X
CX = Y
DX = Pointer to an array of pointers to list entries
EX = Window descriptor
FX = Width
GX = Height
HX = Count of list entries

Inserts a list or a multi-line textbox to a window. Returns the keycode of the
element into AX and element descriptor into BX.


  Scrollbar (AX == 11)
  
BX = X
CX = Y
DX = type
EX = Window descriptor
FX = length in pixels
GX = count of possible values
HX = value to connect

Inserts a scrollbar to a window.

  Text buffer (AX == 29)

BX = X
CX = Y
DX = pointer to null-terminated buffer
EX = window descriptor
FX = max length of buffer
GX = width of textbox
HX = height of textbox

Inserts an user-editable textbox to a window.
