QT has text displays like QLabel, QLineEdit, etc and numerical displays like QSpinBox.

I assume you're using a text based display, lets say QPlainTextEdit (QLabel is better but I didnt know that when writing EEHack... EEHack was my first real QT program!)

m3_get(x,y) should get you an integer, so

Code:
int x = m3_get(0x01,0x02);
...gets you a 16 bit integer as x.

you need to convert that integer to a string to display. so...

Code:
QString s = QString::number(x);
gets you a string representation, base 10, of your integer, as s.

or if you want hex display base 16:

Code:
QString s = QString::number(x,16)
then you go ahead and display that:

Code:
ui->your_text_thing->setPlainText(s);
you can wrap it up into an ugly one liner if you want:

Code:
ui->your_display->setPlainText(QString::number(m3_get(0x01,0x02),16));
or better yet, make a function:

Code:
void controller::your_function_name(byte a, byte b) {
  int x = m3_get(a,b);
  ui->your_display->setPlainText(QString::number(x,16));
}
then just call it when you need it:

Code:
your_function_name(0x05,0x08);