Changing background color of Psychtoolbox fixation point

Question

I took some code posted on a Yahoo help forum and wanted to know how I can modify it to have a grey background on the fixation point. Apologies I am completely new to Psychtoolbox.

screenNum=0;
[window, rect] = Screen('OpenWindow', screenNum, 1);
[X,Y] = RectCenter(rect);
FixCross = [X-1,Y-40,X+1,Y+40;X-40,Y-1,X+40,Y+1];
Screen('FillRect', window, [255,255,255], FixCross');
Screen('Flip', window);
WaitSecs(2)
sca

Answer 1

Just added 'Screen('FillRect', window, [192,192,192]' and it did the job

screenNum=0;
[window, rect] = Screen('OpenWindow', screenNum, 1);
[X,Y] = RectCenter(rect);
FixCross = [X-1,Y-40,X+1,Y+40;X-40,Y-1,X+40,Y+1];
Screen('FillRect', window, [192,192,192])
Screen('FillRect', window, [255,255,255], FixCross');
Screen('Flip', window);
WaitSecs(2)
sca