Trigger Editor: cannot easily input float numbers to specify the known_value for "incoming data" triggers

[davidebriani]

When trying to define a trigger for incoming data events where a comparison on some interface value is desired, the user cannot easily specify the known_value property if it's a float number:

• If written into the JSON editor, the value is immediately discarded.
• To specify it with the UI input field, the user must know to write an integer number, e.g. 12, and only then insert a dot in between the digits, i.e. 1.2.

It should be easier to specify and handle floating point values in the Trigger Editor.