New MainToolBar

Hi All,
I’m a rookie for QGroundControl Software Development and Qt, please forgive me for any mistake.
I want to make a new MainToolBar.qml that display on the bottom of the screen.
I tried to modify code in MainWindowInner.qml, I can add the same MainToolBar at the bottom of the screen (just make for sample).
But when I tried to add a new MainToolBarBottom.qml to the project, it didn’t work.
I don’t know how to add a new qml file, like :/qml/QGroundControl/Controls/MainToolBar.qml
When I add a new file, it add to :/qml/src/ui/toolbar/MainToolBarBottom.qml
And when I run project, Qt have a message “qrc:qml/MainWindowInner.qml:308:5: MainToolBarBottom is not a type”
Please help me for this issue.

Thank you.