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Qt Commercial Support Weekly #21 - Qt Commercial Support Team One-Liner Q&As

Sometimes the support requests that we get can be answered with a single line effectively, so in the spirit of that, in this post I will answer some questions that are answered by a single line.


Q: How can I detect if my build of Qt is static or not in my pro file?
A: In your pro file you can use 'static' on Windows and Linux and 'qt_no_framework' on Mac.


Q: When I delete an object then it crashes, why is this happening?
A: What is most likely to be the case here is you delete an object in a slot or an event handler which expects the object to still exist when it returns, to get around this call deleteLater() on the object.


Q: How can I find out which keyboard modifiers are being held down at any given point?
A: Since Qt 4.8 you can use QApplication::queryKeyboardModifiers() to find out what keyboard modifiers are currently being pressed down.


Q: Why has no one looked at the bug I reported on yet?
A: This is because this is managed by the community and not everything gets looked at right away, if you find a bug that you need a fix for then please contact the support team directly via the customer portal at


Q: Is [insert name here] class or function thread-safe or re-entrant?
A: Check the documentation for the class/function in question, at the top of each class page it indicates whether the class is thread-safe or re-entrant.


Q: Is [insert name here] platform/compiler supported?
A: Check the list at as this indicates all the platforms and compilers that are supported by Qt Commercial.


Q: How do I detect if qmake is generating a Makefile for debug or release in my pro file?
A: You can use the following as a scope - build_pass:CONFIG(debug, debug|release) - to detect for a debug release. For release checking you can replace the first debug instance with release.


Until next time, happy coding! :)