chatgui: stage dropped files through the attachment composer

tools/chatgui/src/messagelist.cpp

@@ -489,6 +489,7 @@ MessageList::MessageList(DbManager* db, AudioRecorder* recorder, QWidget *parent
 
     m_inputBar = new InputBar(m_emojiPanel, recorder, this);
     layout->addWidget(m_inputBar);
+    m_inputBar->installFileDropTarget(m_view->viewport());
 
     connect(m_inputBar, &InputBar::sendMessage, this, [this](const QString &text) {
         if (m_currentChannelId.isEmpty()) {