qt: Make SignVerifyMessageDialog aware of runtime palette change

This change fixes the GUI when changing appearance on macOS.

Author: hebasto

src/qt/signverifymessagedialog.cpp

@@ -283,3 +283,19 @@ bool SignVerifyMessageDialog::eventFilter(QObject *object, QEvent *event)
     }
     return QDialog::eventFilter(object, event);
 }
+
+void SignVerifyMessageDialog::changeEvent(QEvent* e)
+{
+#ifdef Q_OS_MACOS
+    if (e->type() == QEvent::PaletteChange) {
+        ui->addressBookButton_SM->setIcon(platformStyle->SingleColorIcon(QStringLiteral(":/icons/address-book")));
+        ui->pasteButton_SM->setIcon(platformStyle->SingleColorIcon(QStringLiteral(":/icons/editpaste")));
+        ui->copySignatureButton_SM->setIcon(platformStyle->SingleColorIcon(QStringLiteral(":/icons/editcopy")));
+        ui->signMessageButton_SM->setIcon(platformStyle->SingleColorIcon(QStringLiteral(":/icons/edit")));
+        ui->clearButton_SM->setIcon(platformStyle->SingleColorIcon(QStringLiteral(":/icons/remove")));
+        ui->addressBookButton_VM->setIcon(platformStyle->SingleColorIcon(QStringLiteral(":/icons/address-book")));
+        ui->verifyMessageButton_VM->setIcon(platformStyle->SingleColorIcon(QStringLiteral(":/icons/transaction_0")));
+        ui->clearButton_VM->setIcon(platformStyle->SingleColorIcon(QStringLiteral(":/icons/remove")));
+    }
+#endif
+}

src/qt/signverifymessagedialog.h

@@ -31,6 +31,7 @@ class SignVerifyMessageDialog : public QDialog
 
 protected:
     bool eventFilter(QObject *object, QEvent *event) override;
+    void changeEvent(QEvent* e) override;
 
 private:
     Ui::SignVerifyMessageDialog *ui;