Open the PLC master properties dialog at three times its width

Element::editProperty() gave PropertiesEditorDialog no size of its own,
so the dialog fell back to its sizeHint, which is sized for the compact
general-purpose editors it usually hosts. A PLC master instead shows a
six-column IO table that grows horizontally, and the dialog came out
too narrow to read those columns in.

For a master whose type is PLC, resize the dialog to three times its
natural width before exec(), keeping the natural height. The width is
clamped to the available screen so it cannot run off the display, and
every other element type opens exactly as before.

sources/qetgraphicsitem/element.cpp

@@ -39,7 +39,9 @@
 #include "elementtextitemgroup.h"
 #include "iostream"
 
+#include <QApplication>
 #include <QCollator>
+#include <QScreen>
 
 static const QString plcTerminalKeys[] = {
 	QETInformation::ELMT_PLC_T1,
@@ -209,6 +211,21 @@ void Element::editProperty()
 		//with the "text" tab of ElementPropertiesWidget,
 		//the ui freeze, until user press escape key
 		dialog.setWindowModality(Qt::WindowModal);
+
+		// A PLC master carries a 6-column IO table: without an explicit
+		// size the dialog falls back to its (cramped) sizeHint, so open it
+		// at three times its natural width instead. The height stays at
+		// the natural one, and the width never exceeds the screen.
+		const ElementData data = elementData();
+		if (data.m_type == ElementData::Master
+			&& data.m_master_type == ElementData::PLC) {
+			const QSize natural = dialog.sizeHint();
+			int width = natural.width() * 3;
+			if (QScreen *screen = QApplication::primaryScreen())
+				width = qMin(width, screen->availableGeometry().width());
+			dialog.resize(width, natural.height());
+		}
+
 		dialog.exec();
 	}
 }