Easier way for adding flow properties to Blocks in block definition diagrams (#1668)

Dear Dusan,

I was just checking out the block definition diagrams, and I haven't found an easy way to add "flow properties" to blocks. Moreover, I found no way to select the direction of the flow property, which can only be the following: in, out, inout.

When adding flow properties, it should display in the block using the following format:

<direction> <property name>: <item type>

in coolant: Water

inout air: Gas

Maybe you could add a drop down menu into the "Attribute editor" dialog, so that people could choose between normal and flow properties. If it is a flow property, additional fields could activate, so that one could choose the direction and set the multiplicity (if needed). Multiplicity seems to be optional.

Thanks in advance for considering this improvement.