Greetings.
I think the title is self-explanatory. The use case I encountered is a field that is used as a search input. When the user clears it, I have no built-in way of reacting to this to reset the displayed results.
I know a possible workaround would be the very useful and versatile Change Detection custom widget (if you don’t know this one, I really recommend to check it out), but it is rather inconvenient to have to setup this for such a simple task.
@fti This is a valid issue, I also had my struggle with.
Also “clear” does not clear the variable, it empties the string (which is not null)!
btw.: You can vote for your own Suggestion 
After all this time, I’m still usually confused about how Tulip handles empty lists VS null VS empty string VS unset variable values (especially with table queries) and I always have to double-check! I guess they cannot change the behavior without breaking a world-record worthy number of apps 
Still, I think refining the UX could actually make the app editor perfectly usable regarding that behavior if they find a way to make the difference between all these cases more visible (ideally graphically with icons, colors etc.).
Thanks for reminding me 
I wanted to get at least one feedback before doing this.
To be fair, this is not TULIPs fault.
First you initialize a variable. This only means, there is a space, with a name, where you can store data of a specific type.
Then you can store some data there and “nothing” can also be a value. An empty string.
You can imagine it as a null value being “I don’t know, we didn’t decide yet” vs an empty string beeing “here is actually nothing”.
Linke no number at all means “we did’t count yet” while 0 means “we checked and found zero items”.
@thorsten.langner You are completely right - Tulip cannot do much about the values. But it would be very helpful if it was more clear what the “empty” field is currently - whether it is “nothing” or null. Being in low-code/no-code environment, it can be really hard to read that value.
Agree..
Also this should be visible in the Development Players Variable Panel.
(null looks the same as empty)