Having the additional TFTD buttons is nice, however I can't stop thinking the "Expend remaining TUs" button is a hackish and potentially harmful way of making sure your soldier doesn't fire in the enemy turn. Here are my reasons why:
1 - It's not reversible. Once you spend all TUs, you're done. If an alien gets spotted after that, you can no longer move that soldier away from his line of fire or use him to snipe the alien from a long distance.
2 - It forces players to only apply it at the end of the turn, which is a direct consequence of 1 eventually leading to the aforementioned problems, if you spot an enemy target.
3 - It requires a fail-safe. Just two days ago, I was playing TFTD and I swear I couldn't figure out how to activate the expend remaining TUs button. I only learned how by reading the latest nightly log. I take it this isn't exactly good for new players either.
4 - It's still prone to accidents. Yes, it's RMB activated, but that doesn't mean it's entirely foolproof. An accidental RMB click could still throw your entire soldier's turn away.
For these problems I'd like to suggest a different solution: replace the Expend Remaining TUs function with a hold fire function, that instead of depleting the unit of TUs, forbids it to fire during the enemy turn. The pros of this function are as it follows:
. It would be reversible. A simple toggle on/off, like an reaction fire button is all you'd need. If you find an alien that you wanted to shoot after all, you can still do it.
. Allows more tactical flexibility. The player doesn't have to do it exclusively in the end of the turn to avoid regretful situations.
. Doesn't require a fail-safe and it's accident proof.
The only issue I can think of for this, would be that this would have to be a personal toggle, instead of a universal one, like the rest of the reaction buttons currently are. This means that you would individually pick which soldiers would be forbidden to fire, kinda how you already do it for depleting TUs, since if it was universal, it would mean all soldiers would be forbidden to fire. The switch would be reset on all soldiers at the beginning of a new turn. The button should be coloured differently (maybe brown) to mark it's individual nature.
*EDIT* One easier way to implement this to make it, would be to make the button work as in "Expend all remaining TUs at the end of the turn". This would allow the function to remain the same while being completely reversible, although it would still need to be an individual soldier toggle that would be reset at the beginning of the turn.