Question: I have an idea of something that would be nice for the QGIS Composer and I think it doesn't exists yet, despite my research. How can I suggest this feature to QGIS developpers ?

I found this that shows the request but I'm a bit stuck at this point : <https://hub.qgis.org/projects/quantum-gis/issues>

I suppose I'm missing something.

Answer: 
To reporting issues or feature requests on [QGIS issue tracking](https://hub.qgis.org/projects/quantum-gis/issues), you need an OSGeo account. Then just login, go to tab *New issue* and in *Tracker* option choose *Feature request*

[![enter image description here](https://i.stack.imgur.com/i2ENF.png)](https://i.stack.imgur.com/i2ENF.png)

Get OSGeo account here: <https://www.osgeo.org/cgi-bin/ldap_create_user.py>

Also see [QGIS documentation](https://qgis.org/en/site/getinvolved/development/bugreporting.html#bugs-features-and-issues) for bugs, features and issues

*edit:*

QGIS issues were migrated to GitHub (<https://github.com/qgis/QGIS/issues>). For feature request use issue label `Feature Request`.
You could post it at

<http://hub.qgis.org/projects/quantum-gis/issues>

as a feature request. But, as copied from an excellent blog post;

> 
> ...4.
> 
> 
> Ask a developer to make the changes for you. This is not terribly
> effective – you’re basically asking someone to work for free, and take
> time away from their family/job/hobbies/social life to do work for
> you. That said, it does sometimes happen, and here’s a few reasons I
> can think of why:
> 
> 
> * You’ve build up enough “karma” within the project through other
> contributions. If someone has been heavily involved in the
> non-development side of the project (eg translations, documentation,
> helping users out on mailing lists/stackexchange, organising hackfests
> or user groups, etc) then developers are much more likely to want to
> help them out in turn.
> * You’ve got a fantastic idea which has just never occurred to anyone
> before. By bringing it to the attention of a developer you might
> trigger the “wow, I could really benefit from that too!” impulse which
> is hard-wired into some of us!
> 
> 
> It’s a particularly interesting or challenging problem, and sometimes
> developers just like to extend themselves.
> 
> 
> ...
> 
> 
> 

it's more likely you will get it done (for you) when you hire a developer to do this.

source: <http://nyalldawson.net/2016/08/how-to-effectively-get-things-changed-in-qgis/>