sync: from linuxdeepin/dtkwidget

[deepin-ci-robot]

Synchronize source files from linuxdeepin/dtkwidget.

Source-pull-request: linuxdeepin/dtkwidget#572

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关键摘要:

• 将QWidget *follower{nullptr};和QWidget *target{nullptr};更改为QPointer<QWidget> follower;和QPointer<QWidget> target;提高了代码的一致性和可维护性。

是否建议立即修改:

• 否，因为这个提交中的更改已经提高了代码质量。但是，如果有其他地方也使用了原始的指针类型，建议统一修改为QPointer以保持一致性。同时，应该检查是否有必要使用QPointer而不是QWidget *，以适应不同的使用场景。