Added classes to manage simple tabular data of known structure using a

popup containing a wxGrid object.

BasePicker : Abstract class adding a popup to wxPickerBase  styled with
a wxTextCtrl.
BaseGridPicker : Abstract class adding a wxGrid in the popup.

JsonGridPickerCtrl : UI control storing the tabular data in a JSON
array.
LBoundJsonGridPicker : connect JsonGridPicker to database.
LGridJsonCellEditor : use LBoundJsonGridPicker in other wxGrid objects.
LGridJsonCellRenderer : render cell JSON data.

XmlGridPickerCtrl : UI control storing the tabular data in as XML
document.
LBoundXmlGridPicker : connect XmlGridPicker to database.
LGridXmlCellEditor : grid editor for LBoundXmlGridPicker.
LGridXmlCellRenderer : grid renderer for LBoundXmlGridPicker.

JsonHelper and XmlHelper : for applications to quickly get intent value
from database data..

The structure of managed tabular data :

Column 1 : Intent - this is what we want to store/edit. This can be
telephone numbers, email addresses, instant messaging addresses...
any single line piece of information that can exist many times for one
entity (person, company...).
Column 2 : Type - A short description of the intent : 'Home, Work,
Mobile, Fax, Other...'. It is displayed in a non editable wxComboBox.
Column 3 : Preferred - One line of data can be selected as the preferred
one. It is not mandatory, but it must be a single choice.
Column 4 : Notes - single line notes.

Adjust sql scripts and L7.dox.
Applied ANSI formatting style to all files.

Other changes :

Work around a nasty misbehavior.
Grid columns edited by a translated combobox expect full string
data as cell values. LResultSet::BEData() will report these mapped strings,
instead of database real data. LBoundComboBox::IsDirty() will always be
true even if the editor is unchanged once created.
Simplest workaround : disconnect m_BoundComboBox if unchanged.

LGridTextEditor::ProvideFormEditor() : set the form editor's value
explicitely.; wxTextCtrl does not interpret data it receives

LBoundControl::SetNull must be void.

LBoundGrid : Unbind:: instructions should limit to the widget's id, like Bind::

LConnection::GetReturnedKeys should return NULL.
LConnection::SetData should return void.

Notes : wxJSON must be configured with the same prefix as wxWidgets,
here /usr/local/{wxWidgets,wxWidgets-Release}.

L7/special/BasePicker.cpp

@@ -0,0 +1,74 @@
+/* 
+ * File:   BasePicker.cpp
+ * Author: SET - nmset@netcourrier.com
+ * License : LGPL version 2.1
+ * Copyright SET, M. D. - © 2014
+ * 
+ * Created on December 7, 2019, 9:24 PM
+ */
+
+#include "BasePicker.h"
+
+IMPLEMENT_CLASS(BasePicker, wxPickerBase)
+
+BasePicker::BasePicker(wxWindow *parent,
+                       wxWindowID id,
+                       wxSize popupSize,
+                       const wxString& text,
+                       const wxPoint& pos,
+                       const wxSize& size,
+                       long style,
+                       const wxValidator& validator,
+                       const wxString& name)
+: wxPickerBase()
+{
+    m_popup = NULL;
+    m_popupSize = popupSize;
+    wxPickerBase::CreateBase(parent, id, text, pos, size, style, validator, name);
+    wxButton * btn = new wxButton(this, wxID_ANY, _T("↓"), wxDefaultPosition, wxDefaultSize, wxBU_EXACTFIT);
+    SetPickerCtrl(btn);
+    wxPickerBase::PostCreation();
+    GetTextCtrl()->SetEditable(false);
+    SetTextCtrlGrowable(true);
+    SetPickerCtrlGrowable(true);
+}
+
+BasePicker::~BasePicker()
+{
+    delete m_popup;
+}
+
+void BasePicker::CreatePopup()
+{
+    wxDELETE(m_popup);
+    m_popup = new wxPopupTransientWindow(this);
+    wxBoxSizer * sz = new wxBoxSizer(wxVERTICAL);
+    m_popup->SetSizer(sz);
+
+    m_popup->Bind(wxEVT_SHOW, &BasePicker::OnPopupHidden, this);
+}
+
+void BasePicker::DoShowPopup()
+{
+    if (m_popupSize.GetWidth() < 0)
+        m_popupSize.SetWidth(GetClientSize().GetWidth());
+    if (m_popupSize.GetHeight() < 0)
+        m_popupSize.SetHeight(300);
+    m_popup->SetClientSize(m_popupSize);
+    m_popup->GetSizer()->Layout();
+
+    wxScreenDC dc;
+    const int screenWidth = dc.GetSize().GetWidth();
+    const int screenHeight = dc.GetSize().GetHeight();
+    const wxPoint oriPos = GetScreenPosition() + GetClientRect().GetBottomLeft();
+    wxPoint dest(oriPos.x, oriPos.y);
+    if (oriPos.x > (screenWidth - m_popupSize.GetWidth())) dest.x = (screenWidth - m_popupSize.GetWidth());
+    if (oriPos.x < 0) dest.x = 0;
+    if (oriPos.y > (screenHeight - m_popupSize.GetHeight())) dest.y = (screenHeight - m_popupSize.GetHeight());
+    if (oriPos.y < 0) dest.y = 0;
+    if (m_popupSize.GetWidth() > screenWidth) dest.x = 0;
+    if (m_popupSize.GetHeight() > screenHeight) dest.y = 0;
+    m_popup->SetPosition(dest);
+
+    m_popup->Popup();
+}