Keyboard navigation is not supported properly when scrollbar is enabled in generator dialog

[PhilippSalvisberg]

If the generator dialog does not show all parameters either because the dialog is resized or simply too many parameters are defined, then the navigation via keyboard is not intuitive, because the active component (textfield, combobox, checkbox) is not visible in the scroll pane.

The "Add foreign key?" checkbox is active in both screen shots. Navigation through "tab" should adjust the visible part of the scroll pane, to make the checkbox automatically visible. Currently the user needs to scroll himself.