selections can now start outside of a message

This means in the empty space under any available messages

src/messages/messageref.cpp

@@ -275,6 +275,41 @@ const Word *MessageRef::tryGetWordPart(QPoint point)
     return nullptr;
 }
 
+// XXX(pajlada): This is probably not the optimal way to calculate this
+int MessageRef::getLastCharacterIndex() const
+{
+    // find out in which line the cursor is
+    int lineNumber = 0, lineStart = 0, lineEnd = 0;
+
+    for (size_t i = 0; i < this->wordParts.size(); i++) {
+        const WordPart &part = this->wordParts[i];
+
+        if (part.getLineNumber() != lineNumber) {
+            lineStart = i;
+            lineNumber = part.getLineNumber();
+        }
+
+        lineEnd = i + 1;
+    }
+
+    // count up to the cursor
+    int index = 0;
+
+    for (int i = 0; i < lineStart; i++) {
+        const WordPart &part = this->wordParts[i];
+
+        index += part.getWord().isImage() ? 2 : part.getText().length() + 1;
+    }
+
+    for (int i = lineStart; i < lineEnd; i++) {
+        const WordPart &part = this->wordParts[i];
+
+        index += part.getCharacterLength();
+    }
+
+    return index;
+}
+
 int MessageRef::getSelectionIndex(QPoint position)
 {
     if (this->wordParts.size() == 0) {

src/messages/messageref.hpp

@@ -30,6 +30,7 @@ public:
     bool updateBuffer = false;
 
     const Word *tryGetWordPart(QPoint point);
+    int getLastCharacterIndex() const;
     int getSelectionIndex(QPoint position);
 
 private:

src/widgets/channelview.cpp

@@ -1,6 +1,7 @@
 #include "widgets/channelview.hpp"
 #include "channelmanager.hpp"
 #include "colorscheme.hpp"
+#include "debug/log.hpp"
 #include "messages/limitedqueuesnapshot.hpp"
 #include "messages/message.hpp"
 #include "messages/messageref.hpp"
@@ -760,6 +761,20 @@ void ChannelView::mousePressEvent(QMouseEvent *event)
     if (!tryGetMessageAt(event->pos(), message, relativePos, messageIndex)) {
         setCursor(Qt::ArrowCursor);
 
+        auto messages = this->getMessagesSnapshot();
+        if (messages.getLength() == 0) {
+            return;
+        }
+
+        // Start selection at the last message at its last index
+        auto lastMessageIndex = messages.getLength() - 1;
+        auto lastMessage = messages[lastMessageIndex];
+        auto lastCharacterIndex = lastMessage->getLastCharacterIndex();
+
+        SelectionItem selectionItem(lastMessageIndex, lastCharacterIndex);
+        this->setSelection(selectionItem, selectionItem);
+        this->selecting = true;
+
         return;
     }