Hi Mario,
I take the points
In another way I am trying to make it simpler for myself. To do just one think with my mind.
I want to make tiddlers as quick as possible, the make lists of them, and to rearrange them. I want to quickly create heirachies. I think I am building a brainstorming type app.
I am experimenting with drag and drop. I drag a tittle onto a button in TopLeftBar and I get a "new-here", a tiddler tagged with the dragged tiddler. The idea came to me when I was using my TW in the normal way: TW open in left had tab of a browser window. I visit another tab, then, copy some text and return to my TW tab. Normally I would have to click a new-here or new tiddler, I wanted to use a button which was just underneath the browser tab... that's how it started.
Currently the buttons are droppable. I drop a tiddler title onto the button to create a new tiddler of close it, or add a list icon to it. I've appropriated the TagPill to be more of a list. You can now rearrange tagged items in TagPill lists and "drag to tag".
Once I started dragging, I found myself wanting to drag other things and for my drags to perform other actions.
Clicks seem more "final" in a way. And a double-click to clear the river so as to focus attention on a single tiddler seems to resemble a physical punctuation, a physical markup of the mental process perhaps.
I was thinking about Fitt's Law :

My tiddling is more along the lines of an arts practice, developing a personal thinking tool. I am exploring the idea of making a UI which minimises hand eye coordination.
For me, the major effort (if we can call clicking buttons that) is finding the button and moving the curser arround. Once I have "got hold" of the tiddler I want to touch it, onto a droppable widget, click or doiuble click. I want to minimise movement or my eyes! I am getting old, they get sore after a while!
TiddlyMap uses double click for opening tiddlers from the map, maybe thats the place to mine for inspiration
Alex