Access Form Drop down Option

Vianney1200,, if I wanted to give the impression that my Access application had dropdown forms I would try one of two techniques.  First I would try setting the application to Overlapping Windows in the Current Database section of Options.  I would then place my forms on the screen and size them according to the amount of space each one needs.  I would place command buttons on the desktop to display individual forms.   With this technique, the forms float on the screen.  Their positions can be controlled using the properties dialog.  Personally, I don't like using Overlapping Windows but users may like them.  They require too much work to maintain but then again I am over 70.  

Secondly, I would consider using the standard main form/subform technique with parent/child relations (i.e., primary and foreign keys).  I would still need command buttons to display my forms and I could load several of them into memory when Access is started.   My forms can have more than 100 fields, which is a lot.  This is my preferred solution.

I could also load several forms into memory when the application starts.  This technique would give me more control of the sizes and positions of my forms.   I do this now with reports using the Makigami Wall principle for project management.  I can load as many as 17 reports into memory at one time before I run out of memory.  It is not the reports, it's the amount of data in my tables.     

I suppose the reason you want dropdown forms is because your users have large-screen monitors (>24 inches).  I also have one in my home office (32" at 4K).  They are super.  I can imagine users needing multiple forms in an emergency operations center (E-911) or in a help desk center to monitor multiple cases and tasks.  HTH.