re-color a whole image (in Gimp)

Colors -> Map -> Color Exchange

customize stamps (annotations) in Okular

1. Create the icon you want to use for your own stamp and save it in any graphics format supported by Okular (as png)
2. Click the Add button, select type Stamp and enter a name for your stamp.
3. Enter the full path to your custom icon into the dropdown box in the Stamp Symbol group.

Warning: mysqli_fetch_array() expects parameter 1 to be mysqli_result, object given in

A possible reason is a lack of ' after SELECT from when you have a double undescore '__': i.g. "SELECT * from bibliografie__Taylor" could be wrong, try with SELECT * from `bibliografie__Taylor`.

msql order by several fields

You can separe the fields by a comma: .g. "ORDER by author, date"

symlinks on linux decoder

You need to have a relative (like "../../folder/file" or "folder/folder/file"), not an absolute one /(like "/mnt/your-path/file"): this latter indeed is effectual only in your computer, not on decoder.

set links as not visited

You must clear not the cache or cookies, but the browser history.