Zooming bug of my own making

When I zoom elements backed by FramebufferWidget, they draw as if the transformation matrix is being concatenated in the wrong order. It ends up looking like this: [Edit: fixed link]

Once I stop zooming, everything draws correctly.
I don’t doubt that I’m doing something wrong, but I haven’t been able to track it down. Since it only happens while I’m zooming, debugging is difficult.
If someone else has run into a bug like this, I’m interested in what you did to track it down and fix it.

The FramebufferWidget is used like this:

struct DisplayWidget : Widget {
     void draw(const DrawArgs& ) override {

struct Buffer : Widget {
   FramebufferWidget* fb;

   Buffer() {
        fb = new FramebufferWidget();
        auto display = new DisplayWidget();

struct MyWidget : ModuleWidget {
   Buffer* buffer;
   MyWidget(Module* module) {
       buffer = new Buffer();

[Edit #2] I tried to dirty the FramebufferWidget on every redraw triggered by the zoom, but that didn’t help. After some more debugging, I determined that FramebufferWidget::step
is not calling FramebufferWidget::drawFrameBuffer because
APP->window->isFrameOverdue() returns true most of the time while zooming. Setting "frameRateLimit": 0.0 in settings.json improves things, but then the frame buffer creation lags enough that the drawing appears out of sync.

When I have time, I’ll rewrite FramebufferWidget::step to draw directly and avoid creating a frame buffer when it doesn’t have time to draw everything…

[Edit #3] … or I’ll rewrite my module so that while zooming is underway, the Widgets are drawn immediately without a backing FramebufferWidget. I think I can do this by adding the widgets twice, and making only the direct one or the FramebufferWidget one visible …

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