src: Add support for right click events

The current implementation treats left mouse button clicks as a
generic "mouse press" modifier, this commit extends the list of
modifiers by adding a "right mouse click" one.

The proper way to implement this would be to ship the coordinates
of mouse key press events in each `Key` object, and pass whichever
button was clicked as a codepoint value (instead of coordinates
currently), but this would require more work.

This commit allows:

* right clicks to set the cursor of the main selection
* control-right clicks to merge all the selections, and then set
  its cursor

Fixes #843

1 files changed, 15 insertions, 3 deletions

diff --git a/src/input_handler.cc b/src/input_handler.cc
index ade87d04..0d9710dd 100644
--- a/src/input_handler.cc
+++ b/src/input_handler.cc
@@ -92,9 +92,20 @@ struct MouseHandler
         Buffer& buffer = context.buffer();
         BufferCoord cursor;
         auto& selections = context.selections();
-        switch ((Key::Modifiers)(key.modifiers & Key::Modifiers::MouseEvent))
+        const auto key_modifier = (Key::Modifiers)(key.modifiers & Key::Modifiers::MouseEvent);
+        switch (key_modifier)
         {
-        case Key::Modifiers::MousePress:
+        case Key::Modifiers::MousePressRight:
+            m_dragging = false;
+            cursor = context.window().buffer_coord(key.coord());
+            if (key.modifiers & Key::Modifiers::Control)
+                selections = {{selections.begin()->anchor(), cursor}};
+            else
+                selections.main() = {selections.main().anchor(), cursor};
+            selections.sort_and_merge_overlapping();
+            return true;
+
+        case Key::Modifiers::MousePressLeft:
             m_dragging = true;
             m_anchor = context.window().buffer_coord(key.coord());
             if (not (key.modifiers & Key::Modifiers::Control))
@@ -108,7 +119,8 @@ struct MouseHandler
             }
             return true;
 
-        case Key::Modifiers::MouseRelease:
+        case Key::Modifiers::MouseReleaseLeft:
+        case Key::Modifiers::MouseReleaseRight:
             if (not m_dragging)
                 return true;
             m_dragging = false;