When a combinator's user-supplied description is too long to fit in a line, it is displayed wrapped.
View with GUI debug (Ctrl+F5):
GuiDebug-Combinators.jpg (390.26 KiB) Viewed 105 times
The description's gui element doesn't fit the parent element. In other combinators this doesn't seem to affect anything.
In the Arithmetic combinator this seems to affect the length of dividers around combinator's entity description (circled green).