Gui: do not reset tab size to 4 when creating new text editor

src/Gui/DlgEditorImp.cpp

@@ -29,6 +29,7 @@
 #include "DlgEditorImp.h"
 #include "ui_DlgEditor.h"
 #include "PythonEditor.h"
+#include "Tools.h"
 
 
 using namespace Gui;
@@ -169,6 +170,17 @@ void DlgSettingsEditorImp::on_colorButton_changed()
     pythonSyntax->setColor( d->colormap[index].first, col );
 }
 
+void DlgSettingsEditorImp::setEditorTabWidth(int tabWidth)
+{
+    QFontMetrics metric(font());
+    int fontSize = QtTools::horizontalAdvance(metric, QLatin1Char('0'));
+#if QT_VERSION < QT_VERSION_CHECK(5, 10, 0)
+    ui->textEdit1->setTabStopWidth(tabWidth * fontSize);
+#else
+    ui->textEdit1->setTabStopDistance(tabWidth * fontSize);
+#endif
+}
+
 void DlgSettingsEditorImp::saveSettings()
 {
     ui->EnableLineNumber->onSave();
@@ -188,6 +200,8 @@ void DlgSettingsEditorImp::saveSettings()
 
     hGrp->SetInt( "FontSize", ui->fontSize->value() );
     hGrp->SetASCII( "Font", ui->fontFamily->currentText().toLatin1() );
+
+    setEditorTabWidth(ui->tabSize->value());
 }
 
 void DlgSettingsEditorImp::loadSettings()
@@ -200,6 +214,7 @@ void DlgSettingsEditorImp::loadSettings()
     ui->radioTabs->onRestore();
     ui->radioSpaces->onRestore();
 
+    setEditorTabWidth(ui->tabSize->value());
     ui->textEdit1->setPlainText(QString::fromLatin1(
         "# Short Python sample\n"
         "import sys\n"

src/Gui/DlgEditorImp.h

@@ -60,6 +60,7 @@ protected Q_SLOTS:
 
 protected:
     void changeEvent(QEvent *e);
+    void setEditorTabWidth(int);
 
 private:
     std::unique_ptr<Ui_DlgEditorSettings> ui;

src/Gui/TextEdit.cpp

@@ -228,8 +228,6 @@ TextEditor::TextEditor(QWidget* parent)
     setFont(serifFont);
 
     ParameterGrp::handle hPrefGrp = getWindowParameter();
-    // set default to 4 characters
-    hPrefGrp->SetInt( "TabSize", 4 );
     hPrefGrp->Attach( this );
 
     // set colors and font