tdf#87884: basic: fix for UnknownPropertyException

UnoControlTabPageModel had no USERFOMRCONTAINERS property
and this was causing an exception during any attempt to set
its properties.

Change-Id: Icc432d7a431ecd861ac4f00a96ec75165bec168c
Reviewed-on: https://gerrit.libreoffice.org/66801Reviewed-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
Tested-by: Thorsten Behrens <Thorsten.Behrens@CIB.de>
(cherry picked from commit 3deab788)
Reviewed-on: https://gerrit.libreoffice.org/67398
Tested-by: Jenkins
Reviewed-by: Michael Stahl <Michael.Stahl@cib.de>
(cherry picked from commit aa7b71cd)

toolkit/source/controls/tabpagemodel.cxx

@@ -57,6 +57,7 @@ UnoControlTabPageModel::UnoControlTabPageModel( Reference< XComponentContext > c
     ImplRegisterProperty( BASEPROPERTY_TITLE );
     ImplRegisterProperty( BASEPROPERTY_HELPTEXT );
     ImplRegisterProperty( BASEPROPERTY_HELPURL );
+    ImplRegisterProperty( BASEPROPERTY_USERFORMCONTAINEES );
 }
 
 OUString SAL_CALL UnoControlTabPageModel::getImplementationName()
@@ -86,6 +87,12 @@ Any UnoControlTabPageModel::ImplGetDefaultValue( sal_uInt16 nPropId ) const
         case BASEPROPERTY_DEFAULTCONTROL:
             aAny <<= OUString("com.sun.star.awt.tab.UnoControlTabPage");
             break;
+        case BASEPROPERTY_USERFORMCONTAINEES:
+        {
+            // We do not have here any usercontainers (yet?), but let's return something back
+            // so normal properties could be set without triggering UnknownPropertyException
+            return makeAny(true);
+        }
         default:
             aAny = UnoControlModel::ImplGetDefaultValue( nPropId );
     }