text view: Smooth cursor blinking

Fade the text cursor in and out, instead
of abruptly turning it on and off.
5 jobs for wip/textview in 5 minutes and 39 seconds (queued for 2 seconds)
Status Job ID Name Coverage
  Build
passed #362818
fedora-x86_64

00:05:33

passed #362819
win32
msys2-mingw32

00:05:39

 
  Flatpak
manual #362820
allowed to fail manual
flatpak-manual:demo
manual #362822
allowed to fail manual
flatpak-manual:icon-browser
manual #362821
allowed to fail manual
flatpak-manual:widget-factory