Rules between fields, Same fields different tabs, Custom list

[Yuval Maron]

Hey, I have 3 main issues: 

1. Is it possible to set up rules and connections between custom fields without using script runner? For example: once the user select a value from the list (Difficult, Easy, Medium), if he picks easy, then another field (for example: text field) will become required. I'm creating a new bug issue scheme and I need to set up some rules. 

2. Is it possible to have the same field in different tabs at the same issue? For example having the field components in Tab1-details, Tab2- solutions etc. 

3. Is it possible to create a custom pick list which derives it values according to the values the project admin enters? For example: a pick list named Cities, the project admin enters : New York, Berlin, Paris etc. and once I add this custom list to a different issue this values will be shown down the list. 

* Without using add-ons and plugins.

[Nic Brough -Adaptavist-]

1. No, and you can't do it even with Scriptrunner - the framework that Server has for apps is not there in Cloud and the Cloud framework for apps does not support the way Behaviours works.
2. No, a field should only appear in one place, to avoid confusing your people
3. Only components can work that way currently.