Update to usability of rule-based styles widgets.

Rule-based tree widget:
* Label and expression header sections have a larger initial width of 200, with new minimum width of 100 for all sections.
* Resizing of first 3 sections are saved to/restored from QSettings. Last section stretches, so is not saved/restored.
* All items now have tool tips of their content (good for small screens).

Rule editing dialog:
* Expanded width for initial form fields
* Added tool tips for expression and description fields.

src/gui/symbology-ng/qgsrulebasedrendererv2widget.cpp

@@ -26,6 +26,7 @@
 #include "qstring.h"
 
 #include <QMenu>
+#include <QSettings>
 #include <QTreeWidgetItem>
 #include <QVBoxLayout>
 #include <QMessageBox>
@@ -89,6 +90,12 @@ QgsRuleBasedRendererV2Widget::QgsRuleBasedRendererV2Widget( QgsVectorLayer* laye
   connect( btnRenderingOrder, SIGNAL( clicked() ), this, SLOT( setRenderingOrder() ) );
 
   currentRuleChanged();
+
+  // store/restore header section widths
+  connect( viewRules->header(), SIGNAL( sectionResized( int, int, int ) ), this, SLOT( saveSectionWidth( int, int, int ) ) );
+
+  restoreSectionWidths();
+
 }
 
 QgsRuleBasedRendererV2Widget::~QgsRuleBasedRendererV2Widget()
@@ -367,6 +374,27 @@ void QgsRuleBasedRendererV2Widget::setRenderingOrder()
   dlg.exec();
 }
 
+void QgsRuleBasedRendererV2Widget::saveSectionWidth( int section, int oldSize, int newSize )
+{
+  Q_UNUSED( oldSize );
+  // skip last section, as it stretches
+  if ( section == 3 )
+    return;
+  QSettings settings;
+  QString path = "/Windows/RuleBasedTree/sectionWidth/" + QString::number( section );
+  settings.setValue( path, newSize );
+}
+
+void QgsRuleBasedRendererV2Widget::restoreSectionWidths()
+{
+  QSettings settings;
+  QString path = "/Windows/RuleBasedTree/sectionWidth/";
+  QHeaderView* head = viewRules->header();
+  head->resizeSection( 0, settings.value( path + QString::number( 0 ), 200 ).toInt() );
+  head->resizeSection( 1, settings.value( path + QString::number( 1 ), 200 ).toInt() );
+  head->resizeSection( 2, settings.value( path + QString::number( 2 ), 100 ).toInt() );
+}
+
 
 ///////////
 
@@ -379,8 +407,10 @@ QgsRendererRulePropsDialog::QgsRendererRulePropsDialog( QgsRuleBasedRendererV2::
   connect( buttonBox, SIGNAL( rejected() ), this, SLOT( reject() ) );
 
   editFilter->setText( mRule->filterExpression() );
+  editFilter->setToolTip( mRule->filterExpression() );
   editLabel->setText( mRule->label() );
   editDescription->setText( mRule->description() );
+  editDescription->setToolTip( mRule->description() );
 
   if ( mRule->dependsOnScale() )
   {
@@ -518,7 +548,7 @@ QVariant QgsRuleBasedRendererV2Model::data( const QModelIndex &index, int role )
 
   QgsRuleBasedRendererV2::Rule* rule = ruleForIndex( index );
 
-  if ( role == Qt::DisplayRole )
+  if ( role == Qt::DisplayRole || role == Qt::ToolTipRole )
   {
     switch ( index.column() )
     {

src/gui/symbology-ng/qgsrulebasedrendererv2widget.h

@@ -107,6 +107,9 @@ class GUI_EXPORT QgsRuleBasedRendererV2Widget : public QgsRendererV2Widget, priv
 
     void currentRuleChanged( const QModelIndex& current = QModelIndex(), const QModelIndex& previous = QModelIndex() );
 
+    void saveSectionWidth( int section, int oldSize, int newSize );
+    void restoreSectionWidths();
+
   protected:
 
     void refineRule( int type );

src/ui/qgsrendererrulepropsdialogbase.ui

@@ -16,6 +16,9 @@
   <layout class="QVBoxLayout" name="verticalLayout">
    <item>
     <layout class="QFormLayout" name="formLayout">
+     <property name="fieldGrowthPolicy">
+      <enum>QFormLayout::ExpandingFieldsGrow</enum>
+     </property>
      <item row="0" column="0">
       <widget class="QLabel" name="label_1">
        <property name="text">

src/ui/qgsrulebasedrendererv2widget.ui

@@ -37,6 +37,12 @@
      <property name="allColumnsShowFocus">
       <bool>true</bool>
      </property>
+     <attribute name="headerMinimumSectionSize">
+      <number>100</number>
+     </attribute>
+     <attribute name="headerStretchLastSection">
+      <bool>true</bool>
+     </attribute>
     </widget>
    </item>
    <item>