Use setPlaceholderText

labelme/labelDialog.py

@@ -39,7 +39,7 @@ class LabelDialog(QDialog):
     def __init__(self, text="Enter object label", parent=None):
         super(LabelDialog, self).__init__(parent)
         self.edit = QLineEdit()
-        self.edit.setText(text)
+        self.edit.setPlaceholderText(text)
         self.edit.setValidator(labelValidator())
         self.edit.editingFinished.connect(self.postProcess)
         layout = QVBoxLayout()