Why I can't see "Fields" in Textbox Properties->Value->Edit Expressions

[tyur]

Why I can't see "Fields" in Textbox Properties->Value->Edit Expressions ? There are "User", "Globals", "Parameters", "Functions", "Operators". But I can't see Field List. Why ? Thank you.
Sorry for my stupid question.

[tyur]

[tyur]

But when I insert table to the report, it has tree "Fields" in Properties of a tables texboxes. Why I can't see "Fields" tree in a single added Textbox Properties?

[Gankov]

Because in first case textbox don't know which dataset need use.
If you put textbox inside list and set dataset for list. Textbox will show fields from dataset.
Alternatively, you can use aggregate functions for access to fields. Like First(field_name, "dataset_name").

[tyur]

Thank You Andrey
Why I can't move selected textbox with mouse left button press, secondary. Onse changed it position and then It look's like text. And can't select it for move or change properties.