Add debug option to skip cursor-only updates while VRR is active (#1616)

* Add debug option to skip cursor-only updates while VRR is active

* Update niri-config/src/lib.rs

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

* Update src/backend/tty.rs

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

* Update wiki/Configuration:-Debug-Options.md

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

* Update Configuration:-Debug-Options.md

* Update tty.rs

* Update lib.rs

* Update Configuration:-Debug-Options.md

---------

Co-authored-by: Ivan Molodetskikh <yalterz@gmail.com>

1 files changed, 17 insertions, 0 deletions

diff --git a/wiki/Configuration:-Debug-Options.md b/wiki/Configuration:-Debug-Options.md
index 639df325..cf59d8b6 100644
--- a/wiki/Configuration:-Debug-Options.md
+++ b/wiki/Configuration:-Debug-Options.md
@@ -29,6 +29,7 @@ debug {
     disable-monitor-names
     strict-new-window-focus-policy
     honor-xdg-activation-with-invalid-serial 
+    skip-cursor-only-updates-during-vrr
 }
 
 binds {
@@ -275,6 +276,22 @@ debug {
 }
 ```
 
+### `skip-cursor-only-updates-during-vrr`
+
+<sup>Since: next release</sup>
+
+Skips redrawing the screen from cursor input while variable refresh rate is active.
+
+Useful for games where the cursor isn't drawn internally to prevent erratic VRR shifts in response to cursor movement.
+
+Note that the current implementation has some issues, for example when there's nothing redrawing the screen (like a game), the rendering will appear to completely freeze (since cursor movements won't cause redraws).
+
+```kdl
+debug {
+    skip-cursor-only-updates-during-vrr
+}
+```
+
 ### Key Bindings
 
 These are not debug options, but rather key bindings.