FIXME Describe what happens when starting an action.

FIXME What happens on a doubleclick.

FIXME Filetype actions

===== Flag replacement =====
Worker replaces placeholders (flags) with actual file names when starting external programs (and in some other places too). Basically there are two different types: A placeholder can be replaced by the name of the **first** selected entry (file or directory) or by **all** selected entries.

When executing a command Worker builds a temporary list of all selected entries. For the "first selected entry" Worker uses the first entry in this list, for "all selected entries" Worker uses all entries in the list.

However, although it says "first/all selected" not in every case it does what it says. It depends on the context what will be inserted in the list and eventually replaced for a placeholder.
  * No context\\ If you click on a button or press a hotkey the commands in the corresponding command list are executed without a context. This means that all currently selected entries are stored in a temporary list. Using this list Worker replaces all placeholders.  This is what normally is expected to happen.
  * Context\\ There used to be a restriction that for doubleclick actions, drag'n'drop and context menus only the active entry was available. In Worker 2.19.0 this limitation is no more so it works basically just as for the "no context" case. However, the only difference is that {f} will be the highlighted entry and not literally the first one.

Some words about reusing of some entries: In normal operation the entry is removed from the list when it is replaced in a command string. For example using {f} twice will **not** results in a double insertion of the same file name but in the insertion of the first and second selected file. It is possible to prevent this by using the "no unselect" modifier for the flag (in this example {uf}). This way the file remains in the list and will be used for another flag replacement.