[vte] emulation: Do not encode keyboard modifiers in X10 mouse mode

[Egmont Koblinger <egmontkob src gnome org>]

commit 473c4e712881252cc832e31ecf7f2d077f60f70f
Author: Egmont Koblinger <egmont gmail com>
Date:   Mon Feb 11 22:57:13 2019 +0100

    emulation: Do not encode keyboard modifiers in X10 mouse mode
    
    https://gitlab.gnome.org/GNOME/vte/issues/93

 src/vte.cc | 20 +++++++++++---------
 1 file changed, 11 insertions(+), 9 deletions(-)
---
diff --git a/src/vte.cc b/src/vte.cc
index aa1fa3c7..fba8cb73 100644
--- a/src/vte.cc
+++ b/src/vte.cc
@@ -5541,15 +5541,17 @@ Terminal::feed_mouse_event(vte::grid::coords const& rowcol /* confined */,
        }
 
        /* Encode the modifiers. */
-       if (m_modifiers & GDK_SHIFT_MASK) {
-               cb |= 4;
-       }
-       if (m_modifiers & VTE_META_MASK) {
-               cb |= 8;
-       }
-       if (m_modifiers & GDK_CONTROL_MASK) {
-               cb |= 16;
-       }
+        if (m_mouse_tracking_mode >= MOUSE_TRACKING_SEND_XY_ON_BUTTON) {
+                if (m_modifiers & GDK_SHIFT_MASK) {
+                        cb |= 4;
+                }
+                if (m_modifiers & VTE_META_MASK) {
+                        cb |= 8;
+                }
+                if (m_modifiers & GDK_CONTROL_MASK) {
+                        cb |= 16;
+                }
+        }
 
        /* Encode a drag event. */
        if (is_drag) {