if ~exist('x'), x = '[-2*pi, 2*pi]'; end


% Plot f1(x) , f2(x) and f3(x) or f4(x).

figure(1)
T1 = uicontrol('pos',[.03 .03 .07 .07],'string','f1','call', ...
    'fig = 1; set(T1,''back'',''y''); set(T2,''back'',''default'')');
ezplot(f1,x,1)
figure(2)
T2 = uicontrol('pos',[.03 .03 .07 .07],'string','f2','call', ...
    'fig = 2; set(T2,''back'',''y''); set(T1,''back'',''default'')');
ezplot(f2,x,2)
figure(3)
T3 = uicontrol('pos',[.03 .03 .07 .07],'string','f3','Callback',
     'ezplot(f3,x,3)'); 

figure(4)
T4 = uicontrol('pos',[.03 .03 .07 .07],'string','f4','call', ...
    'fig = 4; set(T4,''back'',''y''); set(T1,''back'',''default'')');
ezplot(f4,x,4)