I was wondering if WebGL is considered stable enough to be enabled by default. It makes some PDFs render much faster and it has been off by default for a while now, so we have had quite some time to test it.

If we decide to enable WebGL by default, we should not forget to update https://github.com/mozilla/pdf.js/blob/master/extensions/chromium/preferences_schema.json#L39 as well.

/cc @yurydelendik 
/cc @Snuffleupagus (because IIRC you were testing WebGL too)

PDFViewerApplication.eventBus.dispatch("fileinputchange", {
        source: this,
        fileInput: evt.target,
      });
    });
    
    appConfig.mainContainer.addEventListener("dragover", function (evt) {
      evt.preventDefault();
      evt.dataTransfer.dropEffect = "move";
    });
    appConfig.mainContainer.addEventListener("drop", function (evt) {
      evt.preventDefault();
      const files = evt.dataTransfer.files;
      if (!files || files.length === 0) {
        return;
      }
      PDFViewerApplication.eventBus.dispatch("fileinputchange", {
        source: this,
        fileInput: evt.dataTransfer,
      });
    });
  } else {
    appConfig.toolbar.openFile.hidden = true;
    appConfig.secondaryToolbar.openFileButton.hidden = true;
  }
  if (!PDFViewerApplication.supportsDocumentFonts) {
    AppOptions.set("disableFontFace", true);
    PDFViewerApplication.l10n.get("web_fonts_disabled").then(msg => {
      console.warn(msg);
    });