sync: from linuxdeepin/dtkwidget

[deepin-ci-robot]

Synchronize source files from linuxdeepin/dtkwidget.

Source-pull-request: linuxdeepin/dtkwidget#577

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deepin pr auto review

关键摘要:

• 在DAbstractDialogPrivate::init函数中，对于窗口阴影处理的逻辑可能不正确，因为它在非标题栏模式下设置了Qt::WA_TranslucentBorder属性，但在标题栏模式下没有。建议统一处理这种属性。
• handle->enableBlurWindow()的返回值被直接检查，但没有考虑到可能返回的是一个异常或者无效的值，应该对返回值进行有效的检查。
• 在DDialogPrivate::init函数中，mainLayout和buttonLayout的缩进和空格使用不一致，建议统一代码风格。

是否建议立即修改:

• 是