I am glad you said "warm glue" Ali Baba - reading through this thread I was hoping that someone would distinguish between "hot" glue and "warm" glue. Here is the U.S. anyway, "warm" glue is less permanent and less dangerous to fingers and delicate items. The glue sticks (and glue gun) are smaller scale - "warm glue" is typically used for craft projects and you have to work fast because it cools rapidly. On the other hand, "hot" glue is much more permanent (and much hotter!) and may damage delicate items (and fingers!) or melt some plastics. It is typically used in heavier-duty applications.
I think "warm" glue would work pretty well for temporary Playmobil displays, with some testing beforehand and caution during use.
Thanks for the clarification Anne. I hadn't appreciated the difference.
I took a look at my gluegun and sticks, and the sticks mention high and low temperature applications. The gun is a small one, bought for about $4, and has no temperature control, just a handle to squeeze the glue out and a hole to shove the stick in. Not even an on/off switch, you just pull the plug out of the wall. That was the sort of thing I meant.
The glue gets hot enough to scald your skin if you are careless using it, but cools very quickly. Under no circumstances touch the heating element/nozzle when hot. It is very useful for fixing things you don't want to move again, but can also be used for temporary holds, if used sparingly.