Changing the color cadet blue in .Xdefaults creates a malfunction in tcl-menus containing tabs, e.g.
Solution --> Analysis Type --> Solution Controls
Why does changing colors in .Xdefaults cause tcl-menu malfunction?
Development is aware of this issue with colors that have spaces between the name(e.g. cadet blue).
Unfortunately we cannot correct this - the problem is in the Tcl library.
There is a simple workaround, though, which is to replace the color name with its equivalent octal representation. For "Cadet Blue", it is #5F9EA0.