mm, then, Gildar, if i understand, mod files, at least xml files, can be in any place while into a custom UI directory? Then you overwrite all matching files if this mod contain some of this?
Best way is to copy you prefered ui skin to another directory, like sa_copper_modded, isn't it?
There are two basic types of add-ons for the Enhanced Client.
1. Mods - Independent add-ons that the client knows to add because of ".mod" files.
2. Skins/Partial Skins - Overrides of things that are part of the default skin.
For mods, you want to make sure all the files for the mod are in the same relative location to each other as the author made them. Other than that, they can be placed anywhere within the directory of the skin you are using (but you will want to make sure you are not overwriting any files in the process).
So if you're given a zip with the following contents...
/SomeMod.mod
/SomeMod.lua
/SomeModSpecialSauce/
/SomeModSpecialSauce/SpecialSauce.lua
And you've got a skin that looks like...
/BobsSkin/interface.xml
/BobsSkin/SomeMod.lua
You don't want to put SomeMod directly into the BobsSkin directory. You'll instead want to make a subdirectory (probably called "SomeMod") and add it there instead. Or you might want to keep things organized a little because you plan on adding lots of mods, and add it like this:
/BobsSkin/interface.xml
/BobsSkin/SomeMod.lua
/BobsSkin/Mods/SomeMod/SomeMod.mod
/BobsSkin/Mods/SomeMod/SomeMod.lua
/BobsSkin/Mods/SomeMod/SomeModSpecialSauce/
/BobsSkin/Mods/SomeMod/SomeModSpecialSauce/SpecialSauce.lua
However, since the name of files usually coincides with the contents of the file... if you have two lua files with the same name, you might have problems anyway (but as long as skin and mod authors appropriately name their files and lua constructs, it should be rare to encounter problems).
For skins/partial skins, combining can be difficult. You will often need to overwrite some files, and doing so might cause one of the skins you are combining to break.
Yes, you do need to be careful about overwriting same-named files (though if the names are appropriate, this should rarely be a problem).
Any posibilty of next mod will be Increased Backpack Items Icons?
I don't plan on working on that any time soon, but other modders might.