Implementation for #6216

* Implementation for #6216 - Make number keys select extruder when object treeview has focus
+ deleted unused extruder_selection()
+ Fixed notification after splitting of the solid object

* Follow up 85a10268b9 - OSX implementation
+ Added shortcuts description to the "Keyboard Shortcuts" dialog

* Workaround to use "+/-" and numbers shortcuts on Linux
+ Fixed build on Linux

* OSX specific: fixed a work of keyboard accelerators from numbers on NumPad keyboard

* KBShortcutsDialog: fixed shortcuts for "Preferences" and "Show/Hide 3Dconnexion devices settings dialog, if enabled" under osx
and "Set Printable/Unprintable" and "Set extruder" under Linux
 + OSX specific: Added minimize of the application on "Cmd+M"

* Hot-fix for 6efeb9d6b4

* Removed Linux specific workaround

src/slic3r/GUI/KBShortcutsDialog.cpp

@@ -109,7 +109,11 @@ void KBShortcutsDialog::fill_shortcuts()
             { "0-6", L("Camera view") },
             { "E", L("Show/Hide object/instance labels") },
             // Configuration
+#ifdef __APPLE__
+            { ctrl + ",", L("Preferences") },
+#else
             { ctrl + "P", L("Preferences") },
+#endif
             // Help
             { "?", L("Show keyboard shortcuts list") }
         };
@@ -149,8 +153,13 @@ void KBShortcutsDialog::fill_shortcuts()
             { "Shift+Tab", L("Collapse/Expand the sidebar") },
 #ifdef _WIN32
             { ctrl + "M", L("Show/Hide 3Dconnexion devices settings dialog, if enabled") },
+#else
+#ifdef __APPLE__
+            { ctrl + "Shift+M", L("Show/Hide 3Dconnexion devices settings dialog") },
+            { ctrl + "M", L("Minimize application") },
 #else
             { ctrl + "M", L("Show/Hide 3Dconnexion devices settings dialog") },
+#endif // __APPLE__
 #endif // _WIN32
 #if ENABLE_RENDER_PICKING_PASS
             // Don't localize debugging texts.
@@ -171,6 +180,20 @@ void KBShortcutsDialog::fill_shortcuts()
         };
 
         m_full_shortcuts.push_back({ { _L("Gizmos"), _L("The following shortcuts are applicable when the specified gizmo is active") }, gizmos_shortcuts });
+
+        Shortcuts object_list_shortcuts = {
+#if defined (__linux__)
+            { alt + "P", L("Set selected items as Ptrintable/Unprintable") },
+            { alt + "0", L("Set default extruder for the selected items") },
+            { alt + "1-9", L("Set extruder number for the selected items") },
+#else
+            { "P", L("Set selected items as Ptrintable/Unprintable") },
+            { "0", L("Set default extruder for the selected items") },
+            { "1-9", L("Set extruder number for the selected items") },
+#endif
+        };
+
+        m_full_shortcuts.push_back({ { _L("Objects List"), "" }, object_list_shortcuts });
     }
     else {
         Shortcuts commands_shortcuts = {