Add date onlyBackward limit.

src/DateSelectDialog.h

@@ -7,6 +7,7 @@
 
 #include "dialogs/GUIFormBaseDialog.h"
 class DateSlidePickerBox;
+class QLabel;
 class DateSelectDialog:public  GUIFormBaseDialog{
     Q_OBJECT
 public:
@@ -15,9 +16,14 @@ public:
     QString getSelectedValue();
     void setSelectedValue(const QString& val);
     void showEvent(QShowEvent *) override;
+    void setOnlyBackward(bool val){
+        onlyBackward = val;
+    }
 protected:
     bool updateReferenceData() override;
     DateSlidePickerBox* box;
+    QLabel* lbl_error = nullptr;
+    bool onlyBackward = true;
 };