Qt bug where model dialog moves behind main window

Question

I have a bug that I am having a hard time solving. I have two windows.

Window A is the main window that contains a text box (in this simplified version). The user is able to edit the contents of this text box by clicking on it where Window B appears as a keypad. Besides the buttons for the numbers, there are 2 additional buttons, Enter and Done. If the user changes the value and presses Enter, then the value in the text box is immediately updated. Pressing Done will then exit the window.

However, if the user presses done without having first pressing enter, then a modal dialog will appear asking the user if they would like to save the value. Once a selection has been made, the model dialog and Window B will exit.

The bug occurs when the user enters a value and presses the Done button. When the modal dialog appears, Window B moves behind Window A. What should happen is that Window B stays ontop of Window A. Interestingly enough, when I step through the code, this bug never happens which is making it tricky to pinpoint.

Has anyone every ran into this issue before?

I am currently running Qt 5.9 on the latest version of Linux Mint (as of this writing)

Also, I have prepared a sample project that demonstrates this bug. Due to the larger complexity of it, I was unable to fit it into 1 file. If needed, I might be able to find some time this week to move everything in one file. However, I can post the Dropbox link if permitted.

Answer 1

Maybe the problem stems from a wrong setting of the parent child relationship of the [QDialog][1] classes.

The following passage might be crucial for your application, but it is hard to say, if you don't show a minimal-reproducible-example.

Note: The parent relationship of the dialog does not imply that the dialog will always be stacked on top of the parent window. To ensure that the dialog is always on top, make the dialog modal. This also applies for child windows of the dialog itself. To ensure that child windows of the dialog stay on top of the dialog, make the child windows modal as well.