Yes there is no “simple” way … using “ChangeLabel” may work but that’s very painful and will work for one given histogram. I would recommend to use that way if, for example, you really need such representation for one specific histogram for some publication in some paper.
My issue is actually related to the width of the tpalette, which also affects the size of the “colored area” (where the data are plotted… I don’t know how to call it. Graph maybe…?) of the entire picture. And labels are cropped because of the squared shape of the picture.
I can’t edit the aspect ratio, nor the dimension and the position (it must stay in the center) of the “colored area”.
I’ve hundreds of pictures that I edit after that root makes them, using a bash script that took me an entire day for setting the right numbers. I’m a bit short in time to re-do the entire thing again.