Added explanation about scenery packages managment

docs/faq.md

@@ -71,6 +71,8 @@ Do not choose a package itself (`Europe`) or a folder further down (`Earth nav d
 
 For XPME, this is usually XPME's top folder. For AutoOrtho, it is usually the `scenery` folder in AutoOrtho's folder (for example `z_autoortho\scenery`), after you move it out of `Custom Scenery` (see the next question). Check where the `Earth nav data` folders are: the folder you choose is the one two levels above them.
 
+Have packages from more than one tool? Keep each tool's packages, and the regions downloaded in OrthoStreamXP, in a folder of their own, and choose the one you fly with. See [Packages › One folder per source](packages.md#one-folder-per-source).
+
 ### Can my packages stay in X-Plane's Custom Scenery folder?
 
 No. Move them anywhere else on your PC, for example `D:\OrthoPackages`. OrthoStreamXP shows them in `Custom Scenery` itself while it runs; if they were already there, X-Plane would see each package twice and OrthoStreamXP refuses to start.

docs/first-setup.md

@@ -58,6 +58,7 @@ D:\OrthoPackages\
         ...
 ```
 
+- Keep packages from different tools (Ortho4XP, OrthoStudio XP...) in separate folders, and keep them apart from regions downloaded in OrthoStreamXP: see [Packages › One folder per source](packages.md#one-folder-per-source).
 - Your packages stay unchanged on disk. While OrthoStreamXP runs, they appear in X-Plane's `Custom Scenery` folder with the photos added. When it stops, they disappear from there again.
 - If the hint turns red, *That folder has no scenery packages*, you probably picked one package instead of the folder that holds them: check that each package has an `Earth nav data` folder inside it.
 - If X-Plane's `Custom Scenery` already contains a folder with the same name as one of your packages, you get a warning. Usually another streaming tool still shows that package there; close that tool before you start OrthoStreamXP and check your scenery_packs.ini file.

docs/packages.md

@@ -2,7 +2,7 @@
 
 [User guide](README.md) › Packages
 
-OrthoStreamXP streams photos onto scenery packages: the ground's shape (the mesh) for each area. The quickest way to get them is to download the mesh of a whole region, on the **Packages** page or in the **Scenery packages** step of the setup. You can also use packages of your own, or both together.
+OrthoStreamXP streams photos onto scenery packages: the ground's shape (the mesh) for each area. The quickest way to get them is to download the mesh of a whole region, on the **Packages** page or in the **Scenery packages** step of the setup. You can also use packages of your own; keep them in a folder of their own (see [One folder per source](#one-folder-per-source)).
 
 ![The Packages page, with Australia and the Pacific installed](images/packages.png)
 
@@ -21,12 +21,30 @@ The page shows the exact sizes of the current release.
 
 ## Where they go
 
-Each region is installed as a package of its own in your **scenery packages folder**, beside your own packages. If you download one during the setup and have not chosen a folder yet, it goes to `OrthoStreamXP\Base Packages` in your user folder, and that folder becomes your scenery packages folder.
-
-Your own packages stay **above** the downloaded regions in X-Plane's scenery list. Where both cover the same area, X-Plane shows yours.
+Each region is installed as a package of its own in the **scenery packages folder** chosen in [Settings › Folders](settings.md#folders). If you download one during the setup and have not chosen a folder yet, it goes to `OrthoStreamXP\Base Packages` in your user folder, and that folder becomes your scenery packages folder.
 
 Leave about 1.7 times the download size free on the drive: the files take more room once they are unpacked.
 
+## One folder per source
+
+Keep the downloaded regions in a folder of their own, and the packages of each other tool (Ortho4XP, OrthoStudio XP, XPME, AutoOrtho) in theirs. For example:
+
+```
+D:\Scenery\OrthoStream\    <- the regions downloaded in OrthoStreamXP
+D:\Scenery\Ortho4XP\       <- your Ortho4XP tiles
+D:\Scenery\OrthoStudio\    <- your OrthoStudio XP packages
+```
+
+Why:
+
+- **No doubled scenery.** A downloaded region covers a whole continent. Packages from two sources for the same area bring two meshes, and often two sets of roads, forests and buildings, which can show twice.
+- **Each tool keeps its own folder.** Ortho4XP, OrthoStudio XP and the others update and delete their packages in their folders. Mixed with packages from elsewhere, it is easy to delete or overwrite the wrong one, and hard to tell which tool a package (and a problem with it) comes from.
+- **Easy to switch.** To fly with another source, choose its folder in [Settings › Folders](settings.md#folders), with the scenery stopped. Your packages stay as they are, and each keeps its textures in the cache.
+
+OrthoStreamXP uses one scenery packages folder at a time, so you fly with one source at a time.
+
+The **Packages** page installs into the folder chosen at that moment, shown at the top of the page. Before you download a region, check that it is your folder for downloaded regions, not your own packages' folder. Don't have one yet? Choose a new, empty folder in [Settings › Folders](settings.md#folders), then install. Home warns that no scenery packages were found until the first region is in it.
+
 ## Roads, forests and buildings
 
 A square of a downloaded mesh no longer shows X-Plane's own roads, forests and buildings. **Roads, forests and buildings** downloads them with each region, into one shared package, `OrthoStream_Overlays`. Turn it off if another package of yours already brings them. The choice applies to the next region you install or update.

docs/settings.md

@@ -36,7 +36,7 @@ Each card shows the imagery zoom, the metres per pixel, roughly how long a new a
 ![Settings: Folders](images/settings-folders.png)
 
 - **X-Plane folder:** the X-Plane installation where the packages appear (in its `Custom Scenery` folder).
-- **Scenery packages folder:** the parent folder of your packages. The line below it lists the packages found.
+- **Scenery packages folder:** the parent folder of your packages. The line below it lists the packages found. Keep the packages of each source (regions downloaded in OrthoStreamXP, Ortho4XP, OrthoStudio XP...) in a folder of their own, and choose here the one you fly with: see [Packages › One folder per source](packages.md#one-folder-per-source).
 - **Cache folder:** where the textures are kept. The line below it shows the free space and how much a new area takes at the current texture size.
 
 ## Pictures and download