Column accepting number values only

[JimmyMcNulty]

What do you mean by int or float columns?

I tried something like:
Display widget "Default" - Type: "Float".
Edit widget "Default".
The XML definition looks like this:

<element name="publish_1_time_work_hours" width="179px" edit="true">
<display widget="default">
<type>float</type>
</display>
</element>

and

<element name="publish_1_time_work_hours" width="179px"/>

This will be still a text column. For input and for calculations as well.

I tried several things already and maybe I can't just get it right, because some of the initial columns work right away sort of hard coded?

Initial column sthpw/task.actual_duration:
Display widget is "tactic.ui.common.SimpleTableElementWdg".
Edit widget is "Default".
This is working as number column right away.

Creating a new column with the same adjustments doesn't give the same result. It would be still a text column.

I feel really lost with this, because I don't see any reason, why this could be so difficult to achieve. What do I miss here? What would be the "normal" way of creating int or float columns?

The Tactic version is 4.4 at work, but I'm getting the same issue with my privat 4.8 Tactic.
I even tried to do this with python. Getting the variable from the column field works just fine, converting it to float is giving me an empty field. But anyway, this should work with just expression language.

Thanks in advance for any helpful advice.