Add stubs for editor handling

Cargo.lock

@@ -100,6 +100,12 @@ dependencies = [
  "lazy_static",
 ]
 
+[[package]]
+name = "cty"
+version = "0.2.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "b365fabc795046672053e29c954733ec3b05e4be654ab130fe8f1f94d7051f35"
+
 [[package]]
 name = "gain"
 version = "0.1.0"
@@ -154,6 +160,7 @@ dependencies = [
  "lazy_static",
  "nih_plug_derive",
  "parking_lot",
+ "raw-window-handle",
  "serde",
  "serde_json",
  "vst3-sys",
@@ -209,6 +216,15 @@ dependencies = [
  "proc-macro2",
 ]
 
+[[package]]
+name = "raw-window-handle"
+version = "0.4.2"
+source = "registry+https://github.com/rust-lang/crates.io-index"
+checksum = "fba75eee94a9d5273a68c9e1e105d9cffe1ef700532325788389e5a83e2522b7"
+dependencies = [
+ "cty",
+]
+
 [[package]]
 name = "redox_syscall"
 version = "0.2.10"