mouse: Implement horizontal scroll. #3450

- Code from Vim source.
- Removed the check for 'guioptions'
- mouse_spec.lua: test <ScrollWheelLeft> and <ScrollWheelRight>
- Move horizontal scroll logic to mouse.c
- Remove 'gui_' from the function names
- Renamed variables to be more specific (as opposed to generic p, w).
- Marked some functions as `static`

1 files changed, 31 insertions, 0 deletions

diff --git a/test/functional/ui/mouse_spec.lua b/test/functional/ui/mouse_spec.lua
index da9d6a0cd2..d0d791308b 100644
--- a/test/functional/ui/mouse_spec.lua
+++ b/test/functional/ui/mouse_spec.lua
@@ -426,4 +426,35 @@ describe('Mouse input', function()
                                                            |
     ]])
   end)
+
+  it('horizontal scrolling', function()
+    feed("<esc>:set nowrap<cr>")
+
+    feed("a <esc>20Ab<esc>")
+    screen:expect([[
+                               |
+                               |
+      bbbbbbbbbbbbbbb^b         |
+      ~                        |
+                               |
+    ]])
+
+    feed("<ScrollWheelLeft><0,0>")
+    screen:expect([[
+                               |
+                               |
+      n bbbbbbbbbbbbbbbbbbb^b   |
+      ~                        |
+                               |
+    ]])
+
+    feed("^<ScrollWheelRight><0,0>")
+    screen:expect([[
+      g                        |
+                               |
+      ^t and selection bbbbbbbbb|
+      ~                        |
+                               |
+    ]])
+  end)
 end)