This is one of my peeves about Glest in general (although if this is fixed in any version, please notify me). When I select, say, 5 worker units to build a building, only the first of those five will build it, and the rest will do nothing. All other commands apply to all units in a selected group except build. So when I select a group of workers, I want them all to go to the construction place (but not get in the way of the building) and when the building is built, repair the building.
The second, but related improvement is as follows. When I send a worker to build a building, sometimes there are other units doing their other, independent tasks at the same time (e.g. mining, walking, etc.), and they sometimes get in the way of a building I am trying to build. This is undesirable. The way I want it to work is for the unit who is actually building the building to wait at the spot for several seconds, and then build it when the location opens up. An additional possibility is that after I have given the command to build a building, I want units to avoid walking on that space.