introduce new helper class Core::Utils::TreeWidgetColumnStretcher

and use it for some options dialogs.

The class fixes QTreeWidget to resize all columns to contents, except one
stretching column. As opposed to standard QTreeWidget, all columns are
still interactively resizable.

src/libs/utils/treewidgetcolumnstretcher.cpp

@@ -0,0 +1,36 @@
+#include "treewidgetcolumnstretcher.h"
+#include <QtGui/QTreeWidget>
+#include <QtGui/QHideEvent>
+#include <QtGui/QHeaderView>
+using namespace Core::Utils;
+
+TreeWidgetColumnStretcher::TreeWidgetColumnStretcher(QTreeWidget *treeWidget, int columnToStretch)
+        : QObject(treeWidget->header()), m_columnToStretch(columnToStretch)
+{
+    parent()->installEventFilter(this);
+    QHideEvent fake;
+    TreeWidgetColumnStretcher::eventFilter(parent(), &fake);
+}
+
+bool TreeWidgetColumnStretcher::eventFilter(QObject *obj, QEvent *ev)
+{
+    if (obj == parent()) {
+        if (ev->type() == QEvent::Show) {
+            QHeaderView *hv = qobject_cast<QHeaderView*>(obj);
+            for (int i = 0; i < hv->count(); ++i)
+                hv->setResizeMode(i, QHeaderView::Interactive);
+        } else if (ev->type() == QEvent::Hide) {
+            QHeaderView *hv = qobject_cast<QHeaderView*>(obj);
+            for (int i = 0; i < hv->count(); ++i)
+                hv->setResizeMode(i, i == m_columnToStretch ? QHeaderView::Stretch : QHeaderView::ResizeToContents);
+        } else if (ev->type() == QEvent::Resize) {
+            QHeaderView *hv = qobject_cast<QHeaderView*>(obj);
+            if (hv->resizeMode(m_columnToStretch) == QHeaderView::Interactive) {
+                QResizeEvent *re = static_cast<QResizeEvent*>(ev);
+                int diff = re->size().width() - re->oldSize().width() ;
+                hv->resizeSection(m_columnToStretch, qMax(32, hv->sectionSize(1) + diff));
+            }
+        }
+    }
+    return false;
+}