GLFW flicker during resize when rendering from secondary thread - c

Question

I'm working with GLFW3 + OpenGL in C under Windows 7 64-bit. Since responsive resizing is very important to my application I'm using a secondary thread for logic + rendering loops so rendering won't be interrupted when the UI thread blocks (e.g. when the user holds down the mouse on the window frame).
This works great except that it sometimes causes the contents of my window to flicker while the user is resizing the window. I suspect there's something I still don't fully understand about the consequences of rendering from a secondary thread and the possible interactions with window resizing - this is my first time working with multithreading.
Here's a minimal code sample that reproduces the problem:
#include <GL/gl3w.h>
#include <GLFW/glfw3.h>
#include <pthread.h>
GLFWwindow* window;
void *threadfun(void *arg);
int main () {
pthread_t mythread;
glfwInit();
window = glfwCreateWindow(640, 480, "Test", NULL, NULL);
pthread_create(&mythread, NULL, &threadfun, (void *)NULL);
while (!glfwWindowShouldClose(window)) glfwWaitEvents();
pthread_join(mythread, NULL);
glfwDestroyWindow(window);
glfwTerminate();
return 0;
}
void *threadfun (void *arg) {
glfwMakeContextCurrent(window);
gl3wInit();
glClearColor(0.0f, 0.5f, 0.0f, 1.0f);
while (!glfwWindowShouldClose(window)) {
glClear(GL_COLOR_BUFFER_BIT);
glfwSwapBuffers(window);
}
}
(I'm compiling with mingw-w64 x86_64-6.3.0-posix-seh-rt_v5-rev1 in case that's relevant.)