Im looking for a way to implement ST-code into the visualization element without creating a helper POU or method in my device/application tree.

Like visualization properties are evaluated at each VISU_TASK cycle I want to be able to create own ST code which interacts with the visualization interface variables.

To be more specific I want to have a property which executes user defined ST-code at each VISU_TASK cycle exactly like its already possible for Input Configuration on various mouse and dialog events. Also a property for initialization (so only executed once) and a timed property would be nice.

With the situation right now I'll have to create a POU function which handles the ST-code and misuse a property, like the text variable, to execute this POU function at each VISU_TASK cycle.

Or does it exist and I don't know it?

I think you want to implement client side scripting?
Maybe creating HTML5 objects is an option, because the JavaScript is executed on the client side.

See html5

I think what you want is a declaration period function for the page, but unfortunately CODESYS does not have it.

I found a way to do it:

You can use, for example, the text variable property of any visualization element and call a function in it.

Example: Write a test POU as a function (FUN), like MyTestFun which need a boolean Variable as an input value.

Now write into the text variable property:

MyTestFun(bBooleanValue)

Thats it. The function is called at each visu_task cycle.