Quote Originally Posted by numbat View Post
You need to insert a column as well. The insertRow which takes a QStandardItem does this automatically.
Qt Code:
  1. if (childItemIndex.isValid()) {
  2. isSuccess = model.insertRow(0, childItemIndex); // make a grandchild, but the item does not appear
  3. isSuccess = model.insertColumn(0, childItemIndex); // Need this...
  4. }
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Your advice has solved the problem.
Thank you very much.