[3.7] bpo-33951: IDLE test_configdialog: call page.update in setUpClass (GH-7892) by miss-islington · Pull Request #7896

[3.7] bpo-33951: IDLE test_configdialog: call page.update in setUpClass (GH-7892) by miss-islington · Pull Request #7896 · python/cpython

…thonGH-7892)

This avoids a failure in at least one case when running only a single
test method rather than all tests in the module.

The issue came up when testing the following on Windows 10 Pro 64-bit:
HighPageTest.test_highlight_target_text_mouse
(cherry picked from commit 2af9f5d)

Co-authored-by: Tal Einat <taleinat+github@gmail.com>