How to edit Qt4 source and make changes apply

Basically, I have a change to be done in /usr/src/qt/src/src/gui/kernel/qclipboard_x11.cpp There is a 10s timeout that causes apps to hang on shutdown (search the file for the word "reasonable"). Not very reasonable, in fact. For illustration, this is what I want to mitigate - I can't open another instance of Okular until the 10 seconds timeout ends. okular(9173) Okular::Utils::realDpiY: Pix: 1080 MM: 285 okular(9173) Okular::Utils::realDpiX: Pix: 1920 MM: 508 okular(9173) Okular::DocumentPrivate::openDocumentInternal: Output DPI: QSizeF(96, 96.2526) ... (window is closed) ... (10 seconds later) ... QClipboard: Unable to receive an event from the clipboard manager in a reasonable time Here I should be able to fix it: XEvent event; // waiting until the clipboard manager fetches the content. if (!X11->clipboardWaitForEvent(ownerId, SelectionNotify, &event, /*HERE->*/ 10000, true)) { qWarning("QClipboard: Unable to receive an event from the " "clipboard manager in a reasonable time"); } I've changed this to 3 seconds, which should be much better. How to make the changes apply? Is there some makefile to run to rebuild Qt from these sources, or am I doing it completely wrong? I assume there's some qt library object file that needs to be rebuilt, but I can't find a way to do it. Thanks. btw. it's Arch install with Xfce, if it's relevant in any way