One trap to be aware of is that the edit text widget cannot be used to edit a field of the tiddler that contains it. Each keypress results in the tiddler being re-rendered, which loses the cursor position within the text field.
I thought that was resolved in TW5.2.0. Based on current documentation, me thinks I likely misunderstood whether or not TW5.2.0 resolved the "trap."
Regardless, do note: in some circumstances, the trap does not apply. However, in other circumstances, the trap does apply. Although not a problem in certain circumstances, I'm thinking best to always avoid use of edit text widget to edit a field of a tiddler in which the edit text widget exists.
Please download the attached and drag into TiddlyWiki.com to be aware of the trap.
Apologies if I missed any already existing discussion about this.