Backported the advanced BarBoxes features from 4.x:

* Added BoxBarCount option.
* Added "set_iface_tag_text" and "add_iface_tag" script functions.
* Now number of simultaneously displayed boxes depends on game res.
* Updated documents.

artifacts/scripting/sfall function notes.txt

@@ -50,7 +50,7 @@ has_fake_trait and has_fake_perk return the number of levels the player has of t
 
 perk_add_mode, set_selectable_perk, set_perkbox_title, hide_real_perks, show_real_perks and clear_selectable_perks control the behaviour of the select a perk box. set_selectable_perk can be used to add additional items by setting the 'active' parameter to 1, and to remove them again by setting it to 0. set_perkbox_title can be used to change the title of the box, or by using "" it will be set back to the default. hide and show_real_perks can be used to prevent the dialog from displaying any of the original 119 perks. perk_add_mode modifies what happens when a fake perk is selected from the perks dialog. It is treated as a set of flags - if bit 1 is set then it is added to the player's traits, if bit 2 is set it is added to the player's perks, and if bit 3 is set it is removed from the list of selectable perks. The default is 0x2. clear_selectable_perks restores the dialog to its default state.
 
-show_iface_tag, hide_iface_tag and is_iface_tag_active relate to the boxes that appear above the interface such as SNEAK and LEVEL. You can use 3 for LEVEL and 4 for ADDICT, or the range from 5 to 9 for custom boxes. Remember to add your messages to intrface.msg and set up the font colours in ddraw.ini if you're going to use custom boxes. Starting from sfall 3.8.12, is_iface_tag_active can also be used to check 0 for SNEAK, 1 for POISONED, and 2 for RADIATED.
+show_iface_tag, hide_iface_tag and is_iface_tag_active relate to the boxes that appear above the interface such as SNEAK and LEVEL. You can use 3 for LEVEL and 4 for ADDICT, or the range from 5 to (4 + the value of BoxBarCount in ddraw.ini) for custom boxes. Remember to add your messages to intrface.msg and set up the font colours in ddraw.ini if you're going to use custom boxes. Starting from sfall 3.8.12, is_iface_tag_active can also be used to check 0 for SNEAK, 1 for POISONED, and 2 for RADIATED.
 
 get/set_bodypart_hit_modifier alter the hit percentage modifiers for aiming at specific bodyparts. Valid bodypart id's are from 0 to 8. Changes are not saved, and will reset to the defaults (or to the values specified in ddraw.ini if they exist) at each reload.
 
@@ -462,6 +462,16 @@ Some utility/math functions are available:
 > int sfall_func0("attack_is_aimed")
 - returns 1 if the aimed attack mode is selected, 0 otherwise
 
+> void sfall_func3("set_iface_tag_text", int tag, string text, int color)
+- sets the text messages and colors for custom notification boxes to the interface without the need to add messages to intrface.msg and set up the font colors in ddraw.ini
+- tag value is the same as used in show_iface_tag, hide_iface_tag, and is_iface_tag_active. The valid range is from 5 to (4 + the value of BoxBarCount in ddraw.ini) or the number of the last custom box added using the add_ifaca_tag function
+- The text is limited to 19 characters
+- available colors: 0 - green, 1 - red, 2 - white, 3 - yellow, 4 - dark yellow, 5 - blue, 6 - purple, 7 - dull pink
+
+> int sfall_func0("add_iface_tag")
+- adds one custom box to the current boxes, and returns the number of the added tag (-1 if the tags limit is exceeded)
+- The maximum number of boxes is limited to 126 tags
+
 > void sfall_func1("inventory_redraw", int invSide)
 - redraws inventory list in the inventory/use inventory item on/loot/barter screens
 - invSide specifies which side needs to be redrawn: 0 - the player, 1 - target (container/NPC in loot/barter screens)