Could I change the letter style in a tree that is attached in a window?
Is there any property?
Tree style is defined in classes that are placed the dhtmlxtree.css file.
In case of dhx_skyblue skin you can redefine the following class to change the letter style:
.dhxtree_dhx_skyblue .standartTreeRow {
border-left:1px solid transparent;
border-right:1px solid transparent;
font-family:Tahoma;
font-size:11px !important;
overflow:hidden;
padding:0;
}