210714 2020-04-18 23:21:23 -0700 Using vmax for select <option> font-size adds a noticeable delay to all future interactive events 2020-04-25 21:02:49 -0700 1 1 1 Unclassified WebKit UI Events Safari 13 iPhone / iPad iOS 13 NEW InRadar P2 Normal --- 1 j webkit-unassigned dino simon.fraser thorton webkit-bug-importer wenson_hsieh oldest_to_newest 1643168 0 396894 j 2020-04-18 23:21:23 -0700 Created attachment 396894 Test case reduction I've attached a one-file test case reduction. Interactive elements (a button in this case) are responsive to begin with. Click into the <select> dropdown and out again, and now all future button presses take a few hundred milliseconds to respond. This persists even after a page refresh; only a force refresh seems to fix it. The delay happens to all interactive touch/click events (ie, links, buttons etc). In the test case, the button (toggling the background color) just makes it easier to appreciate the delay, but the delay also applies to opening the <select> dropdown itself. I've put the same test case here: https://jamielinux.github.io/webkit-select-font-size-bug/ Steps to reproduce: 1. Create a <select> dropdown. 2. Style <option> font-size to any vmax value. 3. Load website. 4. Touch events (eg, a button) are responsive. 5. Open the <select> dropdown and close it. 6. All future touch events have a delay of a few hundred milliseconds. 7. Refresh page and problem still persists. 8. Force refresh page and problem resets. Hardware/software details: - iPhone XS Max - iOS 13.4.1 - Both iOS Safari & iOS Firefox 1644533 1 ap 2020-04-22 15:23:59 -0700 I could reproduce this. 1644534 2 webkit-bug-importer 2020-04-22 15:24:12 -0700 <rdar://problem/62214347> 1645744 3 simon.fraser 2020-04-25 21:02:49 -0700 Do we lose fast click somehow? 396894 2020-04-18 23:21:23 -0700 2020-04-18 23:21:23 -0700 Test case reduction index.html text/html 877 j PGh0bWw+CiAgPGhlYWQ+CiAgICA8bWV0YSBjaGFyc2V0PSJ1dGYtOCIgLz4KICAgIDxtZXRhIG5h bWU9InZpZXdwb3J0IiBjb250ZW50PSJ3aWR0aD1kZXZpY2Utd2lkdGgiIC8+CiAgICA8dGl0bGU+ aU9TIFdlYktpdCBCdWc8L3RpdGxlPgogICAgPHN0eWxlPgogICAgICAuYm9keS0tcmVkIHsKICAg ICAgICBiYWNrZ3JvdW5kLWNvbG9yOiBibGFjazsKICAgICAgfQogICAgICAuc2VsZWN0X19vcHRp b24gewogICAgICAgIGZvbnQtc2l6ZTogMXZtYXg7CiAgICAgIH0KICAgIDwvc3R5bGU+CiAgICA8 c2NyaXB0PgogICAgICBmdW5jdGlvbiBiZ1RvZ2dsZSgpIHsKICAgICAgICBjb25zdCBib2R5ID0g ZG9jdW1lbnQuYm9keTsKICAgICAgICBpZiAoYm9keS5jbGFzc0xpc3QuY29udGFpbnMoImJvZHkt LXJlZCIpKSB7CiAgICAgICAgICBib2R5LmNsYXNzTGlzdC5yZW1vdmUoImJvZHktLXJlZCIpOwog ICAgICAgIH0gZWxzZSB7CiAgICAgICAgICBib2R5LmNsYXNzTGlzdC5hZGQoImJvZHktLXJlZCIp OwogICAgICAgIH0KICAgICAgfQogICAgPC9zY3JpcHQ+CiAgPC9oZWFkPgogIDxib2R5PgogICAg PGJ1dHRvbiB0eXBlPSJidXR0b24iIGNsYXNzPSJzZWxlY3RfX2J1dHRvbiIgb25jbGljaz0iYmdU b2dnbGUoKSI+CiAgICAgIENsaWNrIG1lIQogICAgPC9idXR0b24+CiAgICA8c2VsZWN0IG5hbWU9 InNlbGVjdCIgY2xhc3M9InNlbGVjdCIgdmFsdWU9Im9uZSI+CiAgICAgIDxvcHRpb24gdmFsdWU9 Im9uZSIgY2xhc3M9InNlbGVjdF9fb3B0aW9uIj5vbmU8L29wdGlvbj4KICAgICAgPG9wdGlvbiB2 YWx1ZT0idHdvIiBjbGFzcz0ic2VsZWN0X19vcHRpb24iPnR3bzwvb3B0aW9uPgogICAgPC9zZWxl Y3Q+CiAgPC9ib2R5Pgo8L2h0bWw+Cg==