qt: Fixes to the process for selecting an existing hdd image

[cold-brewed]

Summary

In settings -> hdd selection -> existing disk, when you type a filename then select specify, you'll get an error about the file not existing. Sometimes the dialog will still appear for selection, but this seems to vary a little by OS.

The message is mainly because once the file entry loses focus (editingFinished signal) it's connected to fileSelected which then connects to onExistingFileSelected. The file does need to be checked once selected and I believe that was the intent. However, the way the signals are wired up you can actually wind up with the check happening twice: once before selection and once after selection.

I tried to go for a minimal fix without too much impact to the existing logic (which could use some updating, really). I did this by allowing the function to differentiate between the signal received when focus is lost (editingFinished) and when a file is actually selected from a dialog (fileSelected). Now, if you type in an existing image name and then tab out or otherwise remove focus, the CHS / size fields are correctly auto-populated. If the image name does not exist, there is no error dialog displayed. However, the OK button is not enabled, requiring a manual selection.

Additionally, there was another bug where the CHS selection was supposed to be disabled when selecting an existing image. Another event (on_comboBoxFormat_currentIndexChanged) caused it to get re-enabled. This was fixed by moving the section in the constructor to after that event fires (combo box being populated).

Checklist

• I have discussed this with core contributors already

References

N/A