After a lot of experimenting I have the demo code working with the original library and an old version IDE using a different mega pcb, I think mine was susspect.
(Tried your library again on new mega and that still just gives a blank screen)
However I now have noticed two wierd issues, my code is below…
I do have another question regarding the line
I tried changing this to ILI9481 but this gives errors…?
(Does not give errors on your modified library but that displays nothing)
The drawLine test draws a verticle line and should draw a horizontal line joined at the end, but it does not. Its offset…?
The fillRect test draws two boxes which should be 1 pxel apart but they display about 20 pixels apart…?
extern uint8_t SmallFont;
// Setup the LCD
// Draw Lines
myGLCD.drawLine(200, 100, 200, 250);
myGLCD.drawLine(200, 200, 300, 200);
// Draw some filled rectangles
myGLCD.fillRect(200, 100, 450, 140);
myGLCD.fillRect(200, 141, 450,181);