qt: Add WalletFrame::sizeHint

Summary:
This change makes the layout of a WalletFrame widget correct even without loaded wallets.
Previously, the window was very small, and as a result the progress dialog overlay was invisible.

This is a backport of [[bitcoin-core/gui#116 | core-gui#116]]

Test Plan: `src/qt/bitcoin-qt -regtest -resetguisettings -nowallet`

Reviewers: #bitcoin_abc, Fabien

Reviewed By: #bitcoin_abc, Fabien

Differential Revision: https://reviews.bitcoinabc.org/D10680

src/qt/walletframe.cpp

@@ -2,11 +2,12 @@
 // Distributed under the MIT software license, see the accompanying
 // file COPYING or http://www.opensource.org/licenses/mit-license.php.
 
-#include <qt/createwalletdialog.h>
-#include <qt/walletcontroller.h>
 #include <qt/walletframe.h>
 
 #include <qt/bitcoingui.h>
+#include <qt/createwalletdialog.h>
+#include <qt/overviewpage.h>
+#include <qt/walletcontroller.h>
 #include <qt/walletmodel.h>
 #include <qt/walletview.h>
 
@@ -19,7 +20,8 @@
 #include <cassert>
 
 WalletFrame::WalletFrame(const PlatformStyle *_platformStyle, BitcoinGUI *_gui)
-    : QFrame(_gui), gui(_gui), platformStyle(_platformStyle) {
+    : QFrame(_gui), gui(_gui), platformStyle(_platformStyle),
+      m_size_hint(OverviewPage{platformStyle, nullptr}.sizeHint()) {
     // Leave HBox hook for adding a list view later
     QHBoxLayout *walletFrameLayout = new QHBoxLayout(this);
     setContentsMargins(0, 0, 0, 0);

src/qt/walletframe.h

@@ -45,6 +45,8 @@ class WalletFrame : public QFrame {
 
     void showOutOfSyncWarning(bool fShow);
 
+    QSize sizeHint() const override { return m_size_hint; }
+
 Q_SIGNALS:
     /** Notify that the user has requested more information about the
      * out-of-sync warning */
@@ -60,6 +62,8 @@ class WalletFrame : public QFrame {
 
     const PlatformStyle *platformStyle;
 
+    const QSize m_size_hint;
+
 public:
     WalletView *currentWalletView() const;
     WalletModel *currentWalletModel() const;