LibreOffice 25.2 Help
Choose Tools - Macros - Organize Dialogs, and then click New.
Enter a name for the dialog and click OK. To rename the dialog later, right-click the name on the tab and choose Rename.
Click Edit. The Basic dialogue editor opens and contains a blank dialogue.
If you do not see the Toolbox bar, click the arrow next to the Insert Controls icon to open the Toolbox bar.
Click a tool and then drag in the dialogue to create the control.