[chronojump] Fixed crash on checkbutton_force_sensor_ai_b click when no force sensor graph loaded

[Xavier de Blas <xaviblas src gnome org>]

commit f0986cca91604d207f3f3dee2a098dcfa2f20965
Author: Xavier de Blas <xaviblas gmail com>
Date:   Tue Jun 12 23:47:04 2018 +0200

    Fixed crash on checkbutton_force_sensor_ai_b click when no force sensor graph loaded

 glade/app1.glade              | 28 +++++++---------------------
 src/gui/forceSensor.cs        |  3 ++-
 src/gui/forceSensorAnalyze.cs |  5 ++++-
 3 files changed, 13 insertions(+), 23 deletions(-)
---
diff --git a/glade/app1.glade b/glade/app1.glade
index 725b725f..ccfde745 100644
--- a/glade/app1.glade
+++ b/glade/app1.glade
@@ -1753,6 +1753,9 @@
                                                             <placeholder/>
                                                             </child>
                                                             <child>
+                                                            <placeholder/>
+                                                            </child>
+                                                            <child>
                                                             <widget class="GtkLabel" 
id="label_start_selector_jumps">
                                                             <property name="visible">True</property>
                                                             <property name="can_focus">False</property>
@@ -18581,6 +18584,7 @@ Concentric</property>
                                                             <widget class="GtkCheckButton" 
id="checkbutton_force_sensor_ai_b">
                                                             <property name="width_request">30</property>
                                                             <property name="visible">True</property>
+                                                            <property name="sensitive">False</property>
                                                             <property name="can_focus">True</property>
                                                             <property 
name="receives_default">False</property>
                                                             <property name="xalign">1</property>
@@ -19588,27 +19592,6 @@ Concentric</property>
                                                             <placeholder/>
                                                             </child>
                                                             <child>
-                                                            <placeholder/>
-                                                            </child>
-                                                            <child>
-                                                            <placeholder/>
-                                                            </child>
-                                                            <child>
-                                                            <placeholder/>
-                                                            </child>
-                                                            <child>
-                                                            <placeholder/>
-                                                            </child>
-                                                            <child>
-                                                            <placeholder/>
-                                                            </child>
-                                                            <child>
-                                                            <placeholder/>
-                                                            </child>
-                                                            <child>
-                                                            <placeholder/>
-                                                            </child>
-                                                            <child>
                                                             <widget class="GtkLabel" 
id="label_force_sensor_ai_rfd_a">
                                                             <property name="visible">True</property>
                                                             <property name="can_focus">False</property>
@@ -28003,6 +27986,9 @@ then click this button.</property>
                                                             <child>
                                                             <placeholder/>
                                                             </child>
+                                                            <child>
+                                                            <placeholder/>
+                                                            </child>
                                                             </widget>
                                                             <packing>
                                                             <property name="expand">False</property>
diff --git a/src/gui/forceSensor.cs b/src/gui/forceSensor.cs
index 7c1660e7..9b332096 100644
--- a/src/gui/forceSensor.cs
+++ b/src/gui/forceSensor.cs
@@ -725,9 +725,10 @@ LogB.Information(" re C ");
                                        event_execute_label_message.Text = forceSensorNotConnectedString;
 
                                button_force_sensor_image_save_signal.Sensitive = false;
+                               button_force_sensor_analyze_recalculate.Sensitive = false;
                                button_force_sensor_image_save_rfd_auto.Sensitive = false;
                                button_force_sensor_image_save_rfd_manual.Sensitive = false;
-                               button_force_sensor_analyze_recalculate.Sensitive = false;
+                               checkbutton_force_sensor_ai_b.Sensitive = false;
                        }
                        else
                                event_execute_label_message.Text = "";
diff --git a/src/gui/forceSensorAnalyze.cs b/src/gui/forceSensorAnalyze.cs
index 18926e58..cfae70a0 100644
--- a/src/gui/forceSensorAnalyze.cs
+++ b/src/gui/forceSensorAnalyze.cs
@@ -688,6 +688,7 @@ public partial class ChronoJumpWindow
                bool debug = false;
 
                button_force_sensor_image_save_rfd_manual.Sensitive = true;
+               checkbutton_force_sensor_ai_b.Sensitive = true;
                if(checkbutton_force_sensor_ai_b.Active)
                        button_force_sensor_analyze_AB_save.Visible = true;
 
@@ -963,7 +964,9 @@ public partial class ChronoJumpWindow
                else
                        button_force_sensor_analyze_AB_save.Visible = false;
 
-               force_sensor_analyze_instant_calculate_params();
+               if(fsAI != null)
+                       force_sensor_analyze_instant_calculate_params();
+
                forceSensorAIChanged = true; //to actually plot
                force_sensor_ai_drawingarea.QueueDraw(); // -- refresh
        }