cpp-builder: Reactivate dashboard control when a new layout is set

`TdxDashboardControl.Clear` makes the control inactive, so that it does
not show any content (TdxDashboardControl.Active == False).

Remove an unused component declaration.

Co-authored-by: Ilia Nenashev <ilia.nenashev@devexpress.com>

Author: NickVolynkin

CPB/uMainForm.cpp

@@ -74,6 +74,8 @@ void __fastcall TMainForm::LoadLayoutAndState()
 
     if (!DataModule1->mdLayoutsState->IsNull)
         dxDashboardControl1->State->Assign(DataModule1->mdLayoutsState);
+
+	dxDashboardControl1->Active = true;
 }
 //---------------------------------------------------------------------------
 void __fastcall TMainForm::btnDeleteClick(TObject *Sender)
@@ -123,13 +125,14 @@ void __fastcall TMainForm::gvLayoutsFocusedRecordChanged(
         (DataModule1->mdLayouts->State != dsInsert))
     {
         LoadLayoutAndState();
-    }
+	}
 }
 //---------------------------------------------------------------------------
 
 void __fastcall TMainForm::dxDashboardControl1LayoutChanged(
 	TdxCustomDashboardControl *ASender)
 {
+    dxDashboardControl1->Active = true;
 	if (DataModule1->mdLayoutsName->AsString != dxDashboardControl1->DashboardName)
 	{
 		DataModule1->mdLayouts->Append();

CPB/uMainForm.h

@@ -73,7 +73,6 @@ class TMainForm : public TForm
 	TdxLayoutItem *liBtnNew;
 	TdxLayoutGroup *lgButtons;
 	TdxLayoutItem *liBtnDelete;
-	TcxGridDBColumn *gvLayoutsState;
 	void __fastcall btnNewDashboardClick(TObject *Sender);
 	void __fastcall btnDeleteClick(TObject *Sender);
 	void __fastcall btnDesignClick(TObject *Sender);