On mobile (I've only tested my android phone), the QTextEdit initially resizes to the remaining available space when the android keyboard is visible, bringing in a scrollbar if necessary for longer texts - which is intended behavior.

But when editing, if I insert a new line or move the cursor up or down by a line, the QTextEdit "grows" back to its fullscreen size, and renders half of its text and UI under the keyboard.

As another measure, I tried adding a second widget to the QVBoxLayout. Sure enough, it is visible above the keyboard initially when text is being entered, but then disappears under the keyboard when I press enter or move the cursor.

Sometimes, I can bring it back to its correct position/layout/size if I close and reopen the keyboard, but that isn't consistent either.

How do I make the QTextEdit (and any widget in general) not resize or grow when the android on-screen keyboard is still active?

Minimal example:

widget.h

#ifndef WIDGET_H
#define WIDGET_H

#include <QWidget>
#include <QTextEdit>
#include <QLayout>

class Widget : public QWidget {
    Q_OBJECT
    QTextEdit* child;
    QLayout* layout;

public:
    Widget(QWidget *parent = nullptr);
    ~Widget();
};
#endif // WIDGET_H

widget.cpp

#include "widget.h"

Widget::Widget(QWidget *parent)
    : QWidget(parent)
{
    child = new QTextEdit();
    layout = new QVBoxLayout();
    layout->addWidget(child);
    setLayout(layout);
}

Widget::~Widget() {
    delete layout;
    delete child;
}

main.cpp

#include "widget.h"

#include <QApplication>

int main(int argc, char *argv[]) {
    QApplication a(argc, argv);
    Widget w;
    w.show();
    return a.exec();
}

To trigger: Build for android, and then type in 30 lines or so (can be blank), and try to navigate to the bottom or last line - then try moving the cursor one line above, and then back down - the last line (and its text) disappears under the keyboard.