QTabWidget::tabText return string with ampersand (&) prepended (linux plasma-kde)

After addition of tab in a QTabWidget, when I try to get the tab text, I get a string with an ampersand prepended.
I tested it with an environnement kde free (a fresh debian VM with XFCE; either french or english) and I got the usual behaviour, but when I install the package kde-full (with the plasma environnement) I get the wrong behaviour; to be more precise: when I have installed both and at the same time XFCE and KDE(plasma):

• in XFCE: I get the goog behaviour
• in KDE: I got the wrong behaviour

It seems that there is a bad interaction with plasme/KDE:

• right after addition of a tab if I display the label, I get the good text
• but later (another GUI event), I get the bad text

I tested with Windows and all is good.

Description of the snipped code:
----------------------------------------

• through QtCreator creation of an Application with widget
• addition of an QTabWidget with no page
• addition of a pushbutton
• in the MainWindow creator addition of a tab with a label
• when click on the button display of the tab's label

this my snipped code:

-------------------------------
#include "mainwindow.h"
#include "ui_mainwindow.h"
#include <QPlainTextEdit>
#include <QDebug>
MainWindow::MainWindow(QWidget *parent) :
  QMainWindow(parent),
  ui(new Ui::MainWindow)
{
  ui->setupUi(this);
  ui->tabWidget->addTab(new QPlainTextEdit, "a sentence");
}

MainWindow::~MainWindow()
{
  delete ui;
}

void MainWindow::on_pushButton_clicked()
{
  qDebug() << ui->tabWidget->tabText(0);
  // it display in the output window:  "&a sentence"
}
------------------------------

Here the ldd output on the binary:
--------------
linux-vdso.so.1 (0x00007ffff7305000)
libQt5Widgets.so.5 => /home/melidrissi/.root/Applications/Qt5.5.0/5.5/gcc_64/lib/libQt5Widgets.so.5 (0x00007f808e697000)
libQt5Gui.so.5 => /home/melidrissi/.root/Applications/Qt5.5.0/5.5/gcc_64/lib/libQt5Gui.so.5 (0x00007f808de84000)
libQt5Core.so.5 => /home/melidrissi/.root/Applications/Qt5.5.0/5.5/gcc_64/lib/libQt5Core.so.5 (0x00007f808d73f000)
libGL.so.1 => /usr/lib/x86_64-linux-gnu/libGL.so.1 (0x00007f808d4a7000)
libpthread.so.0 => /lib/x86_64-linux-gnu/libpthread.so.0 (0x00007f808d28a000)
libstdc+.so.6 => /usr/lib/x86_64-linux-gnu/libstdc+.so.6 (0x00007f808cf7e000)
libm.so.6 => /lib/x86_64-linux-gnu/libm.so.6 (0x00007f808cc7d000)
libgcc_s.so.1 => /lib/x86_64-linux-gnu/libgcc_s.so.1 (0x00007f808ca67000)
libc.so.6 => /lib/x86_64-linux-gnu/libc.so.6 (0x00007f808c6be000)
libgobject-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgobject-2.0.so.0 (0x00007f808c46c000)
libgthread-2.0.so.0 => /usr/lib/x86_64-linux-gnu/libgthread-2.0.so.0 (0x00007f808c26a000)
librt.so.1 => /lib/x86_64-linux-gnu/librt.so.1 (0x00007f808c062000)
libglib-2.0.so.0 => /lib/x86_64-linux-gnu/libglib-2.0.so.0 (0x00007f808bd53000)
libXext.so.6 => /usr/lib/x86_64-linux-gnu/libXext.so.6 (0x00007f808bb41000)
libX11.so.6 => /usr/lib/x86_64-linux-gnu/libX11.so.6 (0x00007f808b7fe000)
libicui18n.so.54 => /home/melidrissi/.root/Applications/Qt5.5.0/5.5/gcc_64/lib/libicui18n.so.54 (0x00007f808b390000)
libicuuc.so.54 => /home/melidrissi/.root/Applications/Qt5.5.0/5.5/gcc_64/lib/libicuuc.so.54 (0x00007f808afe2000)
libicudata.so.54 => /home/melidrissi/.root/Applications/Qt5.5.0/5.5/gcc_64/lib/libicudata.so.54 (0x00007f80895b8000)
libdl.so.2 => /lib/x86_64-linux-gnu/libdl.so.2 (0x00007f80893b4000)
/lib64/ld-linux-x86-64.so.2 (0x00007f808ef15000)
libexpat.so.1 => /lib/x86_64-linux-gnu/libexpat.so.1 (0x00007f808918b000)
libglapi.so.0 => /usr/lib/x86_64-linux-gnu/libglapi.so.0 (0x00007f8088f5d000)
libXdamage.so.1 => /usr/lib/x86_64-linux-gnu/libXdamage.so.1 (0x00007f8088d5a000)
libXfixes.so.3 => /usr/lib/x86_64-linux-gnu/libXfixes.so.3 (0x00007f8088b54000)
libX11-xcb.so.1 => /usr/lib/x86_64-linux-gnu/libX11-xcb.so.1 (0x00007f8088952000)
libxcb-glx.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-glx.so.0 (0x00007f8088739000)
libxcb-dri2.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri2.so.0 (0x00007f8088534000)
libxcb-dri3.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-dri3.so.0 (0x00007f8088331000)
libxcb-present.so.0 => /usr/lib/x86_64-linux-gnu/libxcb-present.so.0 (0x00007f808812e000)
libxcb-sync.so.1 => /usr/lib/x86_64-linux-gnu/libxcb-sync.so.1 (0x00007f8087f27000)
libxcb.so.1 => /usr/lib/x86_64-linux-gnu/libxcb.so.1 (0x00007f8087d05000)
libxshmfence.so.1 => /usr/lib/x86_64-linux-gnu/libxshmfence.so.1 (0x00007f8087b02000)
libXxf86vm.so.1 => /usr/lib/x86_64-linux-gnu/libXxf86vm.so.1 (0x00007f80878fc000)
libdrm.so.2 => /usr/lib/x86_64-linux-gnu/libdrm.so.2 (0x00007f80876ee000)
libffi.so.6 => /usr/lib/x86_64-linux-gnu/libffi.so.6 (0x00007f80874e5000)
libpcre.so.3 => /lib/x86_64-linux-gnu/libpcre.so.3 (0x00007f8087277000)
libXau.so.6 => /usr/lib/x86_64-linux-gnu/libXau.so.6 (0x00007f8087073000)
libXdmcp.so.6 => /usr/lib/x86_64-linux-gnu/libXdmcp.so.6 (0x00007f8086e6d000)