[LyX/master] Set Local Layout tab stop distance to 4

[Juergen Spitzmueller]

commit c50f40b522884f57b06b94a363f77da1797d1e89
Author: Daniel Ramoeller <d.lyx at web.de>
Date:   Sat Oct 16 09:51:33 2021 +0200

    Set Local Layout tab stop distance to 4
    
    Fix for bug #12395.
---
 src/frontends/qt/GuiDocument.cpp |   13 +++++++++++--
 1 files changed, 11 insertions(+), 2 deletions(-)

diff --git a/src/frontends/qt/GuiDocument.cpp b/src/frontends/qt/GuiDocument.cpp
index 23a1818..1b837f0 100644
--- a/src/frontends/qt/GuiDocument.cpp
+++ b/src/frontends/qt/GuiDocument.cpp
@@ -488,8 +488,7 @@ PreambleModule::PreambleModule(QWidget * parent)
 	connect(editPB, SIGNAL(clicked()), this, SLOT(editExternal()));
 	connect(findLE, SIGNAL(returnPressed()), this, SLOT(findText()));
 	checkFindButton();
-	// https://stackoverflow.com/questions/13027091/how-to-override-tab-width-in-qt
-	const int tabStop = 4;
+	int const tabStop = 4;
 	QFontMetrics metrics(preambleTE->currentFont());
 #if (QT_VERSION >= QT_VERSION_CHECK(5, 11, 0))
 	// horizontalAdvance() is available starting in 5.11.0
@@ -612,6 +611,16 @@ LocalLayout::LocalLayout(QWidget * parent)
 	connect(validatePB, SIGNAL(clicked()), this, SLOT(validatePressed()));
 	connect(convertPB, SIGNAL(clicked()), this, SLOT(convertPressed()));
 	connect(editPB, SIGNAL(clicked()), this, SLOT(editExternal()));
+	// https://stackoverflow.com/questions/13027091/how-to-override-tab-width-in-qt
+	const int tabStop = 4;
+	QFontMetrics metrics(locallayoutTE->currentFont());
+#if (QT_VERSION >= QT_VERSION_CHECK(5, 11, 0))
+	// horizontalAdvance() is available starting in 5.11.0
+	// setTabStopDistance() is available starting in 5.10.0
+	locallayoutTE->setTabStopDistance(tabStop * metrics.horizontalAdvance(' '));
+#else
+	locallayoutTE->setTabStopWidth(tabStop * metrics.width(' '));
+#endif
 }