Adjust the date in wxDatePickerCtrlGeneric after changing range.

Ensure that the current value remains between the lower and upper range
boundaries in the generic implementation, as it was already done by the MSW
one.

src/generic/datectlg.cpp

@@ -409,7 +409,21 @@ bool
 wxDatePickerCtrlGeneric::SetDateRange(const wxDateTime& lowerdate,
                                       const wxDateTime& upperdate)
 {
-    return m_popup->SetDateRange(lowerdate, upperdate);
+    if ( !m_popup->SetDateRange(lowerdate, upperdate) )
+        return false;
+
+    // If the limits were, check that our current value lies between them and
+    // adjust it if it doesn't.
+    const wxDateTime old = GetValue();
+    if ( old.IsValid() )
+    {
+        if ( lowerdate.IsValid() && old < lowerdate )
+            SetValue(lowerdate);
+        else if ( upperdate.IsValid() && old > upperdate )
+            SetValue(upperdate);
+    }
+
+    return true;
 }
 
 
@@ -436,7 +450,7 @@ bool wxDatePickerCtrlGeneric::GetRange(wxDateTime *dt1, wxDateTime *dt2) const
 void
 wxDatePickerCtrlGeneric::SetRange(const wxDateTime &dt1, const wxDateTime &dt2)
 {
-    m_popup->SetDateRange(dt1, dt2);
+    SetDateRange(dt1, dt2);
 }
 
 wxCalendarCtrl *wxDatePickerCtrlGeneric::GetCalendar() const