disable remove button if there are no samples to remove

GUI/View/Views/SampleView.cpp

@@ -97,6 +97,7 @@ SampleView::SampleView()
         editor->setCurrentSample(t);
         onRequestViewInRealspace(t);
         scriptPanel->setCurrentSample(t);
+	updateActions();
     });
 
     connect(editor, &SampleEditor::modified, scriptPanel, &ScriptPanel::onSampleModified);
@@ -110,6 +111,8 @@ SampleView::SampleView()
             &RealspaceWidget::updateScene);
 
     connect(editor, &SampleEditor::modified, gDoc.get(), &ProjectDocument::setModified);
+
+    updateActions();
 }
 
 SampleView::~SampleView()
@@ -180,6 +183,13 @@ void SampleView::setToolbarActions(QToolBar* toolbar)
     connect(m_rm_action, &QAction::triggered, m_set, &SamplesSet::delete_current);
 }
 
+void SampleView::updateActions()
+{
+    bool enabled = m_set->currentIndex() != size_t(-1);
+    m_rm_action->setEnabled(enabled);
+    m_cp_action->setEnabled(enabled);
+}
+
 void SampleView::applySplitterPos()
 {
     QSettings settings;