Explanation:
WordPress includes a "quick edit" function that lets users edit certain post properties (title, categories, etc) from the "All Posts" list. WP calculates the width (colspan attribute) of the inline editor based on the number of <th>'s in the header of the first .widefat table on the page. When PUC and Debug Bar are both active, that first table happens to be the debug info table in our Debug Bar panel. This table does not have a <thead>. As a result, WordPress sets the colspan to zero, making the inline editor unusable.
Fixed by removing the "widefat" class from our debug info tables and adding a bunch of new CSS to emulate WordPress table style.
2edd17e0a5