Height of toolBar?

[lutinbis]

hi,
It s my first message on this forum and I hope You will can help me.

I would Like create a toolBar up to my timline with a shelfLayout inside
But when I do this code, the height of my toolbar as a minimal value to 80 and I dont now Why.
I have the same thing with the scrollLayout but not with formLayout or panelLayout

if (toolBar -ex TBtoolBarTimeLine )deleteUI TBtoolBarTimeLine;

if (shelfLayout -ex shelfLayoutTimeLine )deleteUI shelfLayoutTimeLine;

setParent  MayaWindow ;

string $shelfLayout =  shelfLayout
                    -h 30
                    shelfLayoutTimeLine;

string $tb          =  toolBar
                     -h 30
                    -area "bottom"
                    -content $shelfLayout
                    -allowedArea "bottom"
                     TBtoolBarTimeLine;

Someone have an Idea ?
Thank you by advance

Lutin