Add the optional Qt::MSWindowsFixedSizeDialogHint parameter to all uses of the QInputDialog::getX static functions to silence a Qt/Windows debug mode warning about QWindowsWindow::setGeometry: Unable to set geometry. Increase the size of the unit calculator to eliminate the same warning. Finally, call adjustSize() on the "Unsaved Changes" dialog to silence the warning.
An empty block after a conditional can be a sign of an omission and can decrease maintainability of the code.
Such blocks should contain an explanatory comment to aid future maintainers.