While making the default insertion caret pop a little wider for better accessibility, I ran into an issue where the insertion point ghosted on arrow key presses. Christian Tietze observed the same issue.
My culprit was settings an x offset for the rect inside drawInsertionPoint. While Christian's blog code doesn't include an offset, there's otherwise no difference in our approach.
Below draws wider insertion caret with rounded corners.
class FatRoundInsertionCaretTextView: NSTextView {