SetFocus must be written at the back of the setlayout setting, otherwise it won't work--use Setfocuspolicy to set different focus policies for the control: tab Focus, click Focus, Wheel focus, and no focus

qlineedit* peditor = new Qlineedit (m_strtext);
Peditor->resize (...);
Peditor->move (...);
Scene ()->addwidget (peditor);
Peditor->setfocus ();
Note the order of the two statements in the red font. If reversed, there will be a "qlineedit how to achieve the focus when the input" problem, because focus is immediately out again, resulting in non-input.

In fact, it is also very good understanding: must be placed in the back of the setlayout, otherwise there is no real display, and how can set the focus?

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In addition, there are:

This->activatewindow ();
Pass1_edit->setfocuspolicy (Qt::strongfocus);

When needed, also set the

SetFocus must be written at the back of the setlayout setting, otherwise it won't work--use Setfocuspolicy to set different focus policies for the control: tab Focus, click Focus, Wheel focus, and no focus