ensure webkit/gtk callbacks run on main thread (#1320)

prevent close event being propagated when handled in app
closes #1268
closes #1288

v2/internal/frontend/desktop/linux/frontend.go

@@ -17,6 +17,7 @@ import (
 	"log"
 	"net/http"
 	"os"
+	"runtime"
 	"strconv"
 	"text/template"
 	"unsafe"
@@ -49,6 +50,10 @@ type Frontend struct {
 	servingFromDisk bool
 }
 
+func init() {
+	runtime.LockOSThread()
+}
+
 func NewFrontend(ctx context.Context, appoptions *options.App, myLogger *logger.Logger, appBindings *binding.Bindings, dispatcher frontend.Dispatcher) *Frontend {
 
 	// Set GDK_BACKEND=x11 to prevent warnings