Slot function's concurrent multiple executions

[ChrisW67]

Secondly, using the same code I am not able to reproduce the issue on Windows, I m not sure why.

You cannot reproduce it on Windows because the about() dialog is application modal on Windows: it blocks all input to the parent application while the dialog is active. You can do it on Android because the about() dialog is not modal: it does not block the parent application input so you can click the button multiple times and get multiple non-modal dialogs. I suspect the docs have not kept up with the expanded mobile platform support.

To convince yourself of the serial nature of the slot executions in the single UI thread of execution can I suggest:

void class::slot() {
  qDebug() << "In :" << Q_FUNC_INFO;
  // show non-modal dialog
  qDebug() << "Out:" << Q_FUNC_INFO;
}

void class::slot() {
  qDebug() << "In :" << Q_FUNC_INFO;
  // show non-modal dialog
  qDebug() << "Out:" << Q_FUNC_INFO;
}

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You will see an "Out" for the each "In" before you see another "In" (and before you click OK on the dialog I expect)... even when you click furiously.