Slots items delegate widgets don't fit tables cells on macOS in the "Create Element with Script" dialog

1. Open the Workflow Designer.
2. Click to the "Create element with script" button on the toolbar.
   Expected result: "Create Element with Script" dialog is shown. There are tables for input and output slots. Each table contains one row.
3. Double-click on the row in the input slots table.
   Expected result: a combobox is shown. It doesn't fit the cell size. See the attached screenshot.

The cell size should be increased.