I would suggest
Tomboy, if it's as good (or better) then KDE's equivalent it should work fine.
I usually scribble notes into Vim after calling a setup function to prep my personalized 'outline' options since I use few plugins.
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My
Journal
Thou shalt check the array bounds of all strings (indeed, all arrays), for surely where thou typest ``foo'' someone someday shall type ``supercalifragilisticexpialidocious''.