Hi !
I started having problems in Sql Developer 4.1 (17 and 18 release) on Linux...
In Editor window I can see Cursor, but after page down command Cursor disappears. I tried changing color, but I can't (I don't get puldown menu with colors, or whatever code selection is in Caret Configuration). It seems that Color of Caret is changed into background color (white). I wanted to change Theme, but my Theme Combo is missing, so I couldn't even test if my assumption is right... Were themes removed?
Take care,
Andy