SunView underline spontaneously replaces inverse video

[Kenneth Porter]

Today while reading something in a textedit app in read-only mode, All of
my text windows switched into a state where selecting caused text to be
underlined instead of in inverse video. I no longer was able to
cut-and-paste properly. Is this some SunView feature that I inadvertantly
enabled, or is it a bug? How can I get rid of it without rebooting?

I don't know whether this is a generic SunView problem, or whether it is
specific to my 386i.

Ken (shiva at well.sf.ca.us)