Description of filters, how to construct a filter
A filter is 2 separate things :
	- a Match part : a list of conditions (could be regular expressions, simple substring match, date match, message flag match,...) that are tested on each message to see if it matches (the filter specifies which operator to apply between the conditions : OR/AND).
	- an action part : what to do when the message matches the filter conditions. For now : move/copy/trash the matching messages.

To construct a filter you thus have to set up the conditions list, and the action; these 2 steps have their corresponding page in the notebook on the right side of the new filters dialog box. The left side is the list of all filters.

	- To edit a filter : you select the filter. Then you can change the filter name (the text entry at the top of the right part of the dialog), then choose the operator (OR/AND) to apply on the conditions you also have to set up to build the filter (see below for more on this). Next you go to the "action" page where you specify what to do on match (see below for more on this).
	When you're done you push the apply button (at the bottom of the dialog) to validate the filter (ie the new filter is actually built with all widgets contents). If you select another filter before pushing apply button, all your changes will be lost. At any moment when you edit a filter you can push the revert button on the bottom right of the dialog to return to the previous state of the edited filter.
	- To set up a new filter : you push the new button (at the bottom left part of the dialog), it creates an empty filter named "New Filter" and follow the same steps as when editing a filter.

The action page is really simple, the only thing you have to know is that the text pop-up and sound emission are not yet implemented :). Moreover when you choose move/copy action, you have to fill the text entry with the name of the destination mailbox.

The match page consists of a list containing all the conditions of the filter (in fact only their type : simple for substring match,regular expressions,date for message date matching,flag for message flag matching ie messages that have been replied to or flagged or unread...).
You have 3 buttons at the bottom of the conditions list :
	-"edit" button : the currently selected condition is displayed in a new (modal, that is you can't manipulate any other window until you close it) dialog box. First you have to choose the type of conditions, then depending of the choosen type the bottom part of the dialog will show widgets that you have to fill to describe the conditions (eg for a "simple" condition you will have a text entry that you will fill with the substring to be contained in the specified fields, for a regular expression condition a list will show up that you have to fill with the regular expression to be tested on the message...). For all type you have a common button (but with different names :-), that lets you tell if you want the condition to match on success or on failure (ie it's a logical NOT operator).
	Next you have to choose the fields concerned by the conditions (this is useless for date/flag conditions, and they greyed out) : from,to,cc,subject fields of the header and the body (all part that is convertible to text).
	Then, depending on the type chosen, you will have the last part of the dialog composed of widgets that will let you give the parameter of the condition : substring to look for if it's a "simple" condition, regular expressions list if it's a "regular expression" condition...
	When you're done you have to push the "OK" button to validate or cancel to forget the changes.

	-"new" button : to set up a new condition. It creates an empty "simple", displayed in the "edit" dialog box (see above). Then you build your new condition using this dialog following same steps as above.

I hope this clarifies a bit the UI for these dialog boxes. I'm not really satisfied with it for now, so any comment, criticism (constructive I mean ;-) will be really appreciated.

PS : excuse my poor english that, as you have guessed it, is not my mother tongue :)