Develop Reference

Adding new menu item to right-click (all platforms)

I have seen a lot of software and browser plugins do this. After installing them, they add some menu items to the system right click. Eg. On my PC, SVN added the item "SVN Checkout" to my right-click menu throughout.
On Android, you see Whatsapp adds itself to the Share menu across the entire system, so for every image you want to share, the option for Whatsapp also shows up. Similar stuff is done by Apps like Pocket, which adds the menu item "Save to Pocket"; so when you click on any article, you see "Save to Pocket" in the menu.
Question: How is this done? Is there a cross platform, generic way, or does this have to be done differently for every platform?
I need to provide this functionality to my users across Windows/Linux/Mac and Android/iOS. Any guidance on this is appreciated!
Update: Can this be done using only Java? That way, one solution will work on all platforms with Java
Thanks

No, there is no cross-platform way to do this.
In Windows, you edit the registry.
In Android, you can implement this in as number of different ways using the Android SDK.
Every platform has it's own APIs.
You also have a bit of a flawed mental model when you compare Android and Windows (or and mobile OS with any desktop OS). The features you mention for Android are built into an app running in the operating, while the contextual (right click) menu in Windows and OSX is a feature of the operating system itself.

List of open-source android launchers

What actual launchers are open-source? I need launcher for 2.3+, but not launcher-plus or ADW, because they are not supported already. Stock ICS+ launcher is not compilable for 2.3.

according to the list on wikipedia , only a few of the launchers are open source.
however , a launcher is a very simple app . the UI itself is the one that makes the difference.
if you wish to start from scratch , you can test out a demo of a launcher made by google :
http://developer.android.com/tools/samples/index.html

Android galaxy tab options menu different?

My friend tried my app with his new galaxy tab and it seems it is a little different than the emulator I tested it on. His options menu for the app was dark instead of the white background and you could not really see any of the options and most of the app did not work properly. I made the app on the 2.1 android update and am very stumped I tried searching for something about this but could not find anything. Is there a way to modify to act accordingly if this happens?

Samsung modified a lot of standard themes and images. The only way to fix it, that I found, was to force my own theme and use my own images everywhere.

Since Android 2.3 the menu background has changed to black. But the general color palette for the icons you make shouldn't be that much different. See more here:
Android Menu Design Guidelines
If you wish to have different icons for android version 2.3 and earlier versions put the icons for Android 2.3 and later in a resource folder with -v9 appended to the folder name. Example:
drawable-hdpi-v9
You should do the same thing with notification icons, as android 2.3 really made a big change to the way notification icons should look.
Btw, if you are looking for an easy way to make icons for your application, Roman Nurik's asset studio is really great: http://android-ui-utils.googlecode.com/hg/asset-studio/dist/index.html

Is it possible to configure an Android install to run a single app?

Is it possible to configure the Android OS to run only a single app?
Basically what I want to do is customize an Android device so that it boots up and runs one application only, and for that application to be switched to the front of the screen automatically. Also, when it gets closed, to be started up and switched to again. Any ideas?
Thanks,
-David

One method is to get the source of Android and write your own custom ROM of Android as Octavian wrote.
Another alternative would be to write a custom home app that, well, isn't really a home app (but replaces the default home app intent). See SlideScreen as an example of a non-traditional "home" app.

Yes it is possible. You have to fetch yourself the source codes for Android and basically create a custom ROM. After applying all desired modifications you bake your ROM and install it to your device.
Pretty much all you need to know about the source and the process of compiling the sources are located at Android Sources. You can view the source codes from your browser by following this link.
Hope it helps you a bit. Good luck.

How to re-build the default "Launcher" application?

My goal is to modify the Launcher application and dynamically modify and change the theme.
I saw several 'home' apps at http://www.cyrket.com/p/android/com.stain46.taghome/. It looks like they took the default Home(Launcher) and modified it. How did they do that? What do I need to modify to achieve the same thing?

I have done this with the ICS launcher. You also need to do quite a number of code changes to get it to compile as a normal app because it uses a lot of private internal APIs (despite what Google may have implied). You also need to change the package name. There are two limitations I've found:
There's a filter called TableMaskFilter that isn't available to normal apps. I think this allows the app drawer to be semi-transparent, but I removed uses of it and it looks fine I think.
More critically, it appears there is no way to replicate the widget-adding experience because it requires a permission that only system apps can have. See this question.
Anyway, I put my source here. It compiles and works on the official Galaxy S2 4.0.3, but if you try to add widgets it will crash.
Note, when you're changing the package name, there are places that Eclipse's refactor doesn't notice (e.g. XML layouts). I recommend you do a global text search/replace instead.

The standard Launcher is open source so you can definitely grab it and modify it the way you want. For your app to be used as the Home Screen you will need to specify the correct Intent filter in your AndroidManifest.xml and the user will have to choose your app when they press the Home button. Why don't you grab that code, play with it and come back when you have more questions and more of an idea of what you want to change.

Here i found one stable version Launcher2
I have sharing that GitHub repo. HERE
WIKI of this project :
This project contains the code for the Launcher app that ships with Android Jelly Bean (API 16).
Some minor changes were required from this source code to remove the use of private APIs. These changes have been marked by "// AOSP Change"