ToolWidget-Sketcher: Tool widget basic framework

================================================

Provides a framework to show in the taskbar a taskbox with a tool settings dialog.

src/Mod/Sketcher/Gui/ViewProviderSketch.cpp

@@ -495,7 +495,9 @@ ViewProviderSketch::ViewProviderSketch()
 }
 
 ViewProviderSketch::~ViewProviderSketch()
-{}
+{
+    connectionToolWidget.disconnect();
+}
 
 void ViewProviderSketch::slotUndoDocument(const Gui::Document& /*doc*/)
 {
@@ -3242,10 +3244,12 @@ bool ViewProviderSketch::setEdit(int ModNum)
     }
 
     // start the edit dialog
-    if (sketchDlg)
-        Gui::Control().showDialog(sketchDlg);
-    else
-        Gui::Control().showDialog(new TaskDlgEditSketch(this));
+    if (!sketchDlg)
+        sketchDlg = new TaskDlgEditSketch(this);
+
+    connectionToolWidget = sketchDlg->registerToolWidgetChanged(std::bind(&SketcherGui::ViewProviderSketch::slotToolWidgetChanged, this, sp::_1));
+
+    Gui::Control().showDialog(sketchDlg);
 
     // This call to the solver is needed to initialize the DoF and solve time controls
     // The false parameter indicates that the geometry of the SketchObject shall not be updateData
@@ -3879,6 +3883,12 @@ QIcon ViewProviderSketch::mergeColorfulOverlayIcons(const QIcon& orig) const
     return Gui::ViewProvider::mergeColorfulOverlayIcons(mergedicon);
 }
 
+void ViewProviderSketch::slotToolWidgetChanged(QWidget* newwidget)
+{
+    if (sketchHandler)
+        sketchHandler->toolWidgetChanged(newwidget);
+}
+
 /*************************** functions ViewProviderSketch offers to friends such as
  * DrawHandlerSketch ************************/