qt: Fix TxViewDelegate layout

This change (1) prevents overlapping date and amount strings,
and (2) guaranties that "eye" sign at the end of the watch-only
address/label is always visible.

Github-Pull: bitcoin-core/gui#176
Rebased-From: f0d0479
(cherry picked from commit 7bc4498)

src/qt/forms/overviewpage.ui

@@ -623,6 +623,9 @@
               <property name="horizontalScrollBarPolicy">
                <enum>Qt::ScrollBarAlwaysOff</enum>
               </property>
+              <property name="sizeAdjustPolicy">
+               <enum>QAbstractScrollArea::AdjustToContents</enum>
+              </property>
               <property name="selectionMode">
                <enum>QAbstractItemView::NoSelection</enum>
               </property>

src/qt/overviewpage.cpp

@@ -23,6 +23,9 @@
 #include <QPainter>
 #include <QStatusTipEvent>
 
+#include <algorithm>
+#include <map>
+
 #define DECORATION_SIZE 54
 #define NUM_ITEMS 5
 
@@ -36,7 +39,7 @@ class TxViewDelegate : public QAbstractItemDelegate
         QAbstractItemDelegate(parent), unit(BitcoinUnits::BTC),
         platformStyle(_platformStyle)
     {
-
+        connect(this, &TxViewDelegate::width_changed, this, &TxViewDelegate::sizeHintChanged);
     }
 
     inline void paint(QPainter *painter, const QStyleOptionViewItem &option,
@@ -69,13 +72,15 @@ class TxViewDelegate : public QAbstractItemDelegate
 
         painter->setPen(foreground);
         QRect boundingRect;
-        painter->drawText(addressRect, Qt::AlignLeft|Qt::AlignVCenter, address, &boundingRect);
+        painter->drawText(addressRect, Qt::AlignLeft | Qt::AlignVCenter, address, &boundingRect);
+        int address_rect_min_width = boundingRect.width();
 
         if (index.data(TransactionTableModel::WatchonlyRole).toBool())
         {
             QIcon iconWatchonly = qvariant_cast<QIcon>(index.data(TransactionTableModel::WatchonlyDecorationRole));
             QRect watchonlyRect(boundingRect.right() + 5, mainRect.top()+ypad+halfheight, 16, halfheight);
             iconWatchonly.paint(painter, watchonlyRect);
+            address_rect_min_width += 5 + watchonlyRect.width();
         }
 
         if(amount < 0)
@@ -92,23 +97,41 @@ class TxViewDelegate : public QAbstractItemDelegate
         }
         painter->setPen(foreground);
         QString amountText = index.sibling(index.row(), TransactionTableModel::Amount).data(Qt::DisplayRole).toString();
-        painter->drawText(amountRect, Qt::AlignRight|Qt::AlignVCenter, amountText);
+        QRect amount_bounding_rect;
+        painter->drawText(amountRect, Qt::AlignRight | Qt::AlignVCenter, amountText, &amount_bounding_rect);
 
         painter->setPen(option.palette.color(QPalette::Text));
-        painter->drawText(amountRect, Qt::AlignLeft|Qt::AlignVCenter, GUIUtil::dateTimeStr(date));
+        QRect date_bounding_rect;
+        painter->drawText(amountRect, Qt::AlignLeft | Qt::AlignVCenter, GUIUtil::dateTimeStr(date), &date_bounding_rect);
+
+        const int minimum_width = std::max(address_rect_min_width, amount_bounding_rect.width() + date_bounding_rect.width());
+        const auto search = m_minimum_width.find(index.row());
+        if (search == m_minimum_width.end() || search->second != minimum_width) {
+            m_minimum_width[index.row()] = minimum_width;
+            Q_EMIT width_changed(index);
+        }
 
         painter->restore();
     }
 
     inline QSize sizeHint(const QStyleOptionViewItem &option, const QModelIndex &index) const override
     {
-        return QSize(DECORATION_SIZE, DECORATION_SIZE);
+        const auto search = m_minimum_width.find(index.row());
+        const int minimum_text_width = search == m_minimum_width.end() ? 0 : search->second;
+        return {DECORATION_SIZE + 8 + minimum_text_width, DECORATION_SIZE};
     }
 
     int unit;
-    const PlatformStyle *platformStyle;
 
+Q_SIGNALS:
+    //! An intermediate signal for emitting from the `paint() const` member function.
+    void width_changed(const QModelIndex& index) const;
+
+private:
+    const PlatformStyle* platformStyle;
+    mutable std::map<int, int> m_minimum_width;
 };
+
 #include <qt/overviewpage.moc>
 
 OverviewPage::OverviewPage(const PlatformStyle *platformStyle, QWidget *parent) :