See commits. This is a relatively minor fix meant to last only until we start bigger reworks of the filechooser models and items.
From the main commit:
filethumbnail: Set filechooser::queried after querying Setting this attribute after querying, but before receiving the results, can lead to inappropriate behaviour. This can be reproduced by dragging the scrollbar very quickly in a large directory; after going up and down a few times, some thumbnails will be wrong. Without this branch, "wrong" means they'll show the completely wrong icon or thumbnail, e.g. a folder icon in a video file. With previous commit, "wrong" means they'll be empty even when there is a thumbnail available. The sequence of events that triggers this is as follows: 1. GtkListItem receives a GFileInfo object and passes it to GtkFileThumbnail via expressions 2. `get_thumbnail()` is called, doesn't find a thumbnail 3. `filechooser::queried` is not set yet, so it is set to TRUE and we call `g_file_query_info_async()` 4. **Before `thumbnail_queried_cb` is called**, a new GFileInfo is set, and we cancel the query initiated in the previous step 5. We now have a GFileInfo with `filechooser::queried` set to TRUE, and no thumbnail! This commit fixes that by only setting the `filechooser::queried` attribute after the icon is queried. We need to set it in two situations: when the query is successful, or when the error is not G_IO_ERROR_CANCELLED. That's because the query was cancelled, we didn't really perform it!