Dialogs and windows should be shown with showMaximized().
Other methods such as show() will prevent interaction with the interfaces.
For dialogs: showMaximized() followed by exec(), if necessary.

QMenu::exec() is fine, however, set the minimum width of the menu to the parent's width.
QMenu::exec(point) prevents interaction with the menu's actions.

void class::assign_image(QPushButton *button, const QColor &color)
{
  if(!button)
    return;

  QImage image(QSize(16, 16), QImage::Format_ARGB32);
  QPainter painter(&image);

  image.fill(color);
  button->setIcon(QPixmap::fromImage(image));
}

After a firmware update of 1.0.45, the device's LEDs may not function.
The EWS276-FIT's operating system is some derivative of Unix, perhaps Linux.

1. Log into the device.
2. Proceed to System Manager -> Firmware.
3. Download the current settings via Backup Setting -> Export.
4. Retain a copy of the downloaded file.
5. > tar -vxzf file.tar.gz
6. Edit etc/config/system and locate "config led" sections.
7. For each malfunctioning LED, add:
   a. option brightness '1'
   b. option default '1'
8. > tar -cvzf 1.tar.gz etc
9. Upload 1.tar.gz via System Manager -> Firmware -> Restore New Setting.