How about adding the possibility to switch the weapon hand via LMB/RMB click on the weapon ?
There are some pretty strong reasons to use one-handed weapons, people have done it before and will most probably be doing it in the future.
A somewhat unusual example might be grenade and knife as main weapons and pistol as sidearm (wrote the reasons in my recent post in tactics forum in favorite weapons).
So, how am I supposed to know which arrow button I am supposed to click to switch the visible hand?
I'll try to break it down a bit.
First, the player will have to learn which side is the right side and which is the left side, and that depends on the point of view (facing the player as in original HUD has it the other way round).
Second, if it is like sniper rifle in the main hand, and a grenade in the off-hand, then there is no confusion, but with one-handed weapons in both hands, how am I supposed to know if I need to switch to the left hand or to the right hand?
Third, the 'either one or the other hand' makes the two directional buttons perfectly superfluous.
All this hassle can be avoided by treating it as 'switch hands'.
If there is some principal reason why you want the player to learn which is the right side and which is the left side in your HUD, I think the better solution would be to only show the 'right' button when the left hand is showing and replace it by 'left' button when the right hand is showing (with the additional benefit of indicating which hand it is that is currently visible).
Maybe I'll implement a feature to automagically switch to the right hand weapon when the player switches the soldier, or, even more advanced, implement a feature so the HUD will remember the recently used hand for each soldier to fix this problem...
The extra click (which will very soon become a thousand extra clicks while playing) cannot be avoided if only one hand is shown, and I very much doubt that changing the current system would improve anything.
I was actually not trying to suggest that this minimal HUD should do something differently about this issue, just pointing out the general problem with showing only one hand.
As for the LMB and RMB, I would suggest to get rid of the 'inv' button if LMB on soldier name would duplicate it.
Because clicking on the soldier name is more convenient, and the presence of the 'inv' button does not force players to find that functionality (so the 'inv' button and the other duplicate buttons are hiding the more convenient functionality in a way).
More generally I think making GUI in C should be considered a fossil nowadays.
I am thinking like 'why such nonstandard semi-completely functional solutions and not some GUI framework?' all the time, but I understand such thing might be difficult for this game.
Also, nowadays mouses have wheels, you know : )
The most natural way to, say, switch weapon, would be mouse wheel in my opinion.
Also, scrolling through the list of soldiers could be done with mouse wheel on the soldier name panel, and changing the elevation level (I mean, which floor is shown) would be more natural as mouse wheel on the elevation button.
Ok, the weapon image.
Could be LMB to shoot, and RMB to switch hands.
But I would rather suggest it this way:
LMB = shoot
RMB = reload
wheel (no matter what direction) = switch hands
Also, instead of showing just total reserved TU, I would rather appreciate the name and TU of reaction fire.
And, as pointed out somewhere, there seems to be no reason to use 'one shot reaction fire', and therefore 'reaction fire' vs 'no reaction fire' would be sufficient.
Reaction fire could also be scrollable button (no reaction fire, firemode 1, firemode 2, etc.) somehow, but no idea how that might look like.
So, yeah, the minimal HUD in my mind would look like this:
1) Soldier name.
2) Weapon image (maybe with reaction fire toggle on top of it, say, in lower corner).
3) Crouch toggle.
4) IR-goggles button.
5) Elevation level button (just one, scrollable with mouse wheel, and LMB/RMB if you will).
Anyway, it seems I got like... interested, and made a mockup. Minimalism FTW.