In QtCreator，Just create a qmake project, simply with ui class：
Add a private QToolBar member, and one slot:
In the MainWindow's constructor, create the tb instance and call refresh_toolbar():
Build and run the program, it's memory usage (see at windows task manager) is growing up......
Qt-5.9.9-mingw32-gcc-9.3-i686 is build from source and not affected.
Qt-5.12.9-msvc2019(19.27.29111)-x86_64 is build from source, Qt-5.15.1-dynamic-msvc2019-x86_64 is from https://github.com/martinrotter/qt5-minimalistic-builds/releases/tag/5.15.1 .
|For Gerrit Dashboard: QTBUG-87774|
|355076,1||QObject: cleanup the orphaned connection lists on destruction||6.1||qt/qtbase||Status: NEW||0||0|
|355086,2||QObject: cleanup the orphaned connection lists on destruction||tqtc/lts-5.15||qt/tqtc-qtbase||Status: NEW||+2||0|