adopted ChangeLog. Fixed a minor issue in PTextEdit. Adopted ctests for the new NeXus handling.

src/musredit_qt6/musredit/PTextEdit.cpp

@@ -3570,7 +3570,8 @@ bool PTextEdit::getTheme()
     bool done = false;
     if (QFile::exists(str)) {
       QFile fln(str);
-      fln.open(QIODevice::ReadOnly | QIODevice::Text);
+      if (!fln.open(QIODevice::ReadOnly | QIODevice::Text))
+        return false;
       QTextStream fin(&fln);
       QString line("");
       while (!fin.atEnd() && !done) {