do not block channel send while draining channel

src/App.zig

@@ -143,10 +143,7 @@ pub fn run(self: *App) !void {
 
 /// Drain the mailbox.
 fn drainMailbox(self: *App) !void {
-    var drain = self.mailbox.drain();
+    while (self.mailbox.pop()) |message| {
-    defer drain.deinit();
-
-    while (drain.next()) |message| {
         log.debug("mailbox message={s}", .{@tagName(message)});
         switch (message) {
             .new_window => |msg| _ = try self.newWindow(msg),

src/renderer/Thread.zig

@@ -238,14 +238,7 @@ fn drainMailbox(self: *Thread) !void {
     const zone = trace(@src());
     defer zone.end();
 
-    // This holds the mailbox lock for the duration of the drain. The
+    while (self.mailbox.pop()) |message| {
-    // expectation is that all our message handlers will be non-blocking
-    // ENOUGH to not mess up throughput on producers.
-
-    var drain = self.mailbox.drain();
-    defer drain.deinit();
-
-    while (drain.next()) |message| {
         log.debug("mailbox message={}", .{message});
         switch (message) {
             .focus => |v| {

src/termio/Thread.zig

@@ -162,11 +162,7 @@ fn drainMailbox(self: *Thread) !void {
     // expectation is that all our message handlers will be non-blocking
     // ENOUGH to not mess up throughput on producers.
     var redraw: bool = false;
-    {
+    while (self.mailbox.pop()) |message| {
-        var drain = self.mailbox.drain();
-        defer drain.deinit();
-
-        while (drain.next()) |message| {
         // If we have a message we always redraw
         redraw = true;
 
@@ -181,7 +177,6 @@ fn drainMailbox(self: *Thread) !void {
             },
         }
     }
-    }
 
     // Trigger a redraw after we've drained so we don't waste cyces
     // messaging a redraw.