A muslim has to be a strong person and must behave in a dignified manner at all times.
Natural expression of emotions is fine regardless on happy occasions or on sad occasions.
There come upon muslims times as a community or as individuals when sorrow is unbearable eg look at state of muslims today ie the whole muslim ummah is in terrible state and as a result we are all sad, some more than others. Our reactions to this situation are very different depending on what we know about islam, its benefits and losses and what we know about each other and how we treat each other.
When sons of this ummah are slaughtered before our eyes and when its daughters are insulted before our eyes, it should remind us the days of moses and pharaoh. Yes some of us will take steps that are more appropriate to suit situation and but others will express their emotions in other ways.
Likewise when individuals lose their loves one and their supporting elements, it is easy for others to make unhelpful remarks but difficult to share their sorrow and responsibilities.
Each matter has a context and a perspective so there is no point in trying to condemned the whole thing one way or the other.
The most happy occasion for this ummah was when the prophet established an islamic community and then on its basis he established an islamic state.
The most unhappy occasion was when that state was destroyed and then soon after that the community spirit of this ummah was also destroyed.
The utmost need of the time is to campaign for reestablishment of that community once more and and if there comes about community then work for establishing the divine empire once more for the good of humanity.
So fighting between ummah over little things is actually turning us into a stupid people and energy wasters. If you do not have the bigger picture in front of your mind then whatever else you do is just waste of time. So get to know the bigger picture and get involved to make it in to reality. That is real islam and if you do that then you are a real muslim who can really face the man in the mirror.
http://www.youtube.com/watch?v=eKq3KDWpBNw&feature=related