remove is_split properity in priv since it has a getter method

pkg/opengl/Shader.zig

@@ -23,6 +23,7 @@ pub inline fn create(typ: c.GLenum) errors.Error!Shader {
 
 /// Set the source and compile a shader.
 pub inline fn setSourceAndCompile(s: Shader, source: [:0]const u8) !void {
+    log.info("shader source:{s}", .{source});
     glad.context.ShaderSource.?(s.id, 1, &@as([*c]const u8, @ptrCast(source)), null);
     glad.context.CompileShader.?(s.id);
 

src/apprt/gtk/class/split_tree.zig

@@ -172,9 +172,6 @@ pub const SplitTree = extern struct {
         /// close dialog.
         pending_close: ?Surface.Tree.Node.Handle,
 
-        /// True if the current split tree contains more than one surface
-        is_split: bool = false,
-
         pub var offset: c_int = 0;
     };