PartDesign: [skip ci] support negative values as second length of a pocket

src/Mod/PartDesign/App/FeaturePocket.cpp

@@ -71,6 +71,10 @@ Pocket::Pocket()
     ADD_PROPERTY_TYPE(Offset,(0.0),"Pocket",App::Prop_None,"Offset from face in which pocket will end");
     static const App::PropertyQuantityConstraint::Constraints signedLengthConstraint = {-DBL_MAX, DBL_MAX, 1.0};
     Offset.setConstraints ( &signedLengthConstraint );
+
+    // Remove the constraints and keep the type to allow to accept negative values
+    // https://forum.freecadweb.org/viewtopic.php?f=3&t=52075&p=448410#p447636
+    Length2.setConstraints(nullptr);
 }
 
 short Pocket::mustExecute() const

src/Mod/PartDesign/Gui/TaskPocketParameters.ui

@@ -104,9 +104,6 @@
        <property name="keyboardTracking">
         <bool>false</bool>
        </property>
-       <property name="minimum">
-        <double>0.000000000000000</double>
-       </property>
       </widget>
      </item>
     </layout>