Banner and pads in a canvas

Hi all,
I have a canvas, divided in 4 pads:

TCanvas *c=new TCanvas ("c", "Phase Space Plots", 800, 850); c->Divide(2,2);

I would like to leave a free space in the canvas upper region , as large as two pads, in order to add a pave where writing some output of my script.

I tried to reduce pads occupancy area, by setting pads margins:

c->cd(1); gPad->SetPad(0,0.4,0.5,0.9); c->cd(2); gPad->SetPad(0.5,0.4,1,0.9); c->cd(3); gPad->SetPad(0,0,0.5,0.4); c->cd(4); gPad->SetPad(0.5,0,1,0.4);

but it doesn’t produce the expected picture: the banner space is produced, but the pads height is not the same for all the 4 pads (2 upper pads higher than 2 bottom pads).

Do you have any suggestions?

Thanks!
Anna

It is normal you get different height, that is what you asked for. See pad # 1 and pad # 3 :

c->cd(1);
gPad->SetPad(0,0.4,0.5,0.9);   // H = 0.9-0.4 = 0.5
c->cd(3);
gPad->SetPad(0,0,0.5,0.4);    // H = 0.4-0 = 0.4