Read the second section, labeled "Thumbs vs Touchscreens", which shows the sweet spot for accessing content via left or right thumb or both. The lower corner closest to the base of the thumb is hard to reach. Unless the user was using both thumbs, placing target UI in one of those corners would hurt one-handed users.
Also note which areas are labeled as HARD to reach for either/both thumbs - the location where GTK4 has placed the main buttons in the File Chooser dialog.
Read the second section, labeled "Thumbs vs Touchscreens", which shows the sweet spot for accessing content via left or right thumb or both. The lower corner closest to the base of the thumb is hard to reach. Unless the user was using both thumbs, placing target UI in one of those corners would hurt one-handed users.
Also note which areas are labeled as HARD to reach for either/both thumbs - the location where GTK4 has placed the main buttons in the File Chooser dialog.