Question

After executing the application, user clicks the start button. At the time I want to change the display to different dimensions. But doing that the screen becomes black and images doesn’t paste.

while ( LoopGDK ( ) )
    {

        if(dbMouseClick()==1){
            int x=dbMouseX(), y=dbMouseY();

            if(x>370 && x<498 && y>240 && y<368){
                dbDeleteImage(1);
                dbDeleteImage(2);
                bg_exist=false;
            }
        }
        if(!dbSpriteExist(1)&&bg_exist==false){
            dbSetDisplayMode(800,224,32);
            dbPasteImage(3,0,0);
        }

        dbSprite(2,370,240,2);
        dbPasteImage(1,0,0);
        dbSync ( );
    }

Answer 1

This engine is outdated and almost not used by any one anymore.

There are plenty way better engines out there, full list can be found here

My favourite would be unreal engine

I would suggest to play around with unreal engine since it has way better support and more easy to use features.