Rene,
The DDT designer you downloaded only is for generation of the UI. It was expect that users would be familiar with the DDT command set for changing things like text in a control at runtime, so it is not documented. I assume thinbasic has something similiar to PowerBasic DDT.
In PowerBasic to set a controls caption for example would be like this:
CONTROL SET TEXT hDialogHandle&, ControlID& "Some text"
In the commercial product to work with controls there is an EZGUI command set based on the runtime engine.
In EZGUI 5.0 Pro you don't use handles for dialogs (forms). Instead all forms are referenced by a name.
For example, the create a Form would look like this:
EZ_Form "MyForm", "", "My caption text", 0,0, 60, 20, "C"
To change the forms caption text would be done like this:
EZ_SetText "MyForm", 0, "My new caption text"
To create a button control would be like this:
EZ_Button %MYFORM_BUTTON1, 30, 10, 20, 1.5, "I am a button", "T"
To change the buttons text would be like this:
EZ_SetText "MyForm", %MYFORM_BUTTON1, "Some new text"
For example to add items to a listbox would be done like this:
EZ_AddItems "MyForm", %MYFORM_MYLISTBOX, "Apples|Pears|Oranges|Peaches|Grapes|Watermellons|Lemons|Limes|"
Forms have names and controls have ID's (numbers) which can be represent by a constant if you like.
It is like how we have Street names, but houses have numbers. In EZGUI Forms are like streets (with names) and the controls are like the houses (with numbers).