void main(){
    char options[4][12] = {"Set value 1","Set value 2","Set value 3","Done"};
    int sel=0,val[3];
    
    while(1){
        sel = option_menu(options,sel);
        switch(sel){
            case 0:
              val[0] = value_menu("Val 1",0,100,val[0]);
            break;
            case 1:
              val[1] = value_menu("Val 2",0,100,val[1]);
            break;
            case 2:
              val[2] = value_menu("Val 3",0,100,val[2]);
            break;
            case 3:
              printf("Val 1: %d\nVal 2: %d\nVal 3: %d",val[0],val[1],val[2]);
            return;
        }
    }
}

int option_menu(char options[][],int selected_index){
    int i,sel=selected_index;
    
    while(1){
        //Clear the display
        display_clear();
        
        //Display options
        for(i=0;i<14 && i+sel<_array_size(options);i++){
            printf(" %s\n",options[i+sel]);
        }
        
        //Display widgets
        display_set_xy(0,0);
        printf(">");        
        display_set_xy(27,0);
        printf("-");
        display_set_xy(27,13);
        printf("-");
        
        //Display scroll bar
        display_set_xy(27,(int)(11.*(float)sel/(float)(_array_size(options)-1))+1);
        printf("=");
        
        //Wait until a button is pressed to prevent screen from flashing.
        while(!any_button());
        
        //change selection, checking that the selection stays in bounds
        if(up_button() && sel>0){
            while(up_button());
            sel--;
        }
        else if(down_button() && sel+1<_array_size(options)){
            while(down_button());
            sel++;
        }
        
        //clear the display and return the currently selected option
        if(a_button()){
            while(a_button());
            display_clear();
            return sel;
        }
    }
}

int value_menu(char query[],int min,int max,int default_val){
    int val=default_val;
    
    if(max<min || default_val<min || default_val>max){
        printf("Invalid parameters.\n\nPress A to continue.\n");
        while(!a_button());
        return default_val;
    }
    
    while(1){
        display_clear();
        printf("%s: %d\n\nUp/Down: Change value\nR: Hold to change slowly\nA: submit\n",query,val);
        
        while(!any_button());
        
        if(up_button() && val<max){
            val++;
        } else if(down_button() && val>min){
            val--;
        } else if(a_button()){
            while(a_button());
            display_clear();
            return val;
        }
        
        if(r_button())sleep(.5);
        else sleep(.1);
    }
}