don't use depth range hack in rect case

src/rendering/twn_draw.c

@@ -202,8 +202,6 @@ static void render_2d(void) {
                 const struct QuadBatch batch =
                     collect_rect_batch(current, render_queue_len - i);
 
-                /* TODO: what's even the point? just use OR_EQUAL comparison */
-                set_depth_range((double)batch_count / UINT16_MAX, 1.0);
                 render_rect_batch(current, batch);
 
                 i += batch.size - 1; ++batch_count;

src/rendering/twn_gl_any_rendering.c

@@ -74,6 +74,9 @@ void clear_draw_buffer(void) {
     /* TODO: don't clear color when skybox is applied? */
     /*       for that window should match framebuffer */
     /*       also it is driver dependent, from what i can gather */
+    /* INFO: also, based on below, driver might prefer it staying this way */
+    /*       https://gamedev.stackexchange.com/questions/90344/render-with-const-depth-value */
+    /*       we could optionally load ARB_invalidate_subdata extension if it's available instead */
     glClear(GL_COLOR_BUFFER_BIT |
             GL_DEPTH_BUFFER_BIT |
             GL_STENCIL_BUFFER_BIT);