From XnView Wiki
Show again bit flags
XnView contains numerous dialog boxes with a "Do not show again" option. The "show again" states of these dialogs are stored in a single setting called ShowAgain, in a form of bit flags. It is possible to manually set the "show again" states by combining values from the following list. By default XnView has the first 28-bits set (268435455).
Here's the list of known ShowAgain bit flags:
1 - Multi-page file notice
2 - Lossless jpeg operation notice, viewer.
4 - ???
8 - Meta data save lost
16 - ???
32 - Tip of the day
64 - Saving multi-page file
128 - Lossless jpeg operation notice, browser.
256 - Cancel changes
512 - ???
1024 - ???
2048 - ???
4096 - Are you sure you want to copy to.
8192 - Are you sure you want to move to.
16384 - ???
32768 - ???
65536 - Dialog asking to use tagged or selected files for move and copy to folder.
131072 - Dialog asking to use tagged or selected files for batch convert, batch rename, ...
262144 - This picture will be converted to RGB with 8bits per component.
67108864 - ???
134217728 - ???
If you know any of the missing values please let me know so I can add them to the list.