GUI SpanPropertyForm: rm coupling of span and width (#856)

This resolves #856 (closed).

GUI/View/Device/SpanPropertyForm.cpp

@@ -43,11 +43,11 @@ SpanPropertyForm::SpanPropertyForm(QWidget* parent, const QString& groupTitle,
     m_centerSpinBox = GUI::Util::createDoubleSpinBoxRow(layout, spanProperty->center());
 
     connect(m_widthSpinBox, &DoubleSpinBox::baseValueChanged, [this](double v) {
-	ASSERT(v >= 0); // spin box should have got limits from property
-	if (m_spanProperty->width() == v)
-	    return;
-	m_spanProperty->setWidth(v);
-	emit dataChanged();
+        ASSERT(v >= 0); // spin box should have got limits from property
+        if (m_spanProperty->width() == v)
+            return;
+        m_spanProperty->setWidth(v);
+        emit dataChanged();
     });
 
     connect(m_centerSpinBox, &DoubleSpinBox::baseValueChanged, [this](double v) {