I am using BlueStacks app player with a rooted Android system installed. I use it for WhatsApp and Kik messengers. I like to send pictures to my contacts but the shared folder is not visible in pictures, so I downloaded QuickPic which works Awesome! but one drawback: Some applications still launch the gallery app, and ignore the fact that QuickPic is my default gallery app. I cannot uninstall "gallery" from the apps.. so how do I replace it? Gallery app is limited and unusable for me, I like to browse the directories myself on the SDcard. I also have a terminal available if that's of any help (Android Terminal Emulator). How can I permanently replace the gallery with QuickPic? I cannot choose my own wallpapers because Gallery is launched instead of QuickPic.
Most apps, when they want to choose an image, use an implicit intent, which just says what they want to do, and doesn't specifically name the Gallery app. This means that any app that can perform that action can be started, and if you have more than one, you get the chooser to choose which to launch. This is the normal behaviour.
You won't get a chooser if you've previously clicked Always in the chooser to set one app as the default, or if the calling app uses an explicit intent, naming the Gallery app specifically.
It's best to check the first case. In the device settings, go to the list of all apps, and find the Gallery. Click it to go into that app's info page, then click Clear defaults. If Clear defaults is greyed out, then it's not set as the default for anything.
If you still don't get a chooser, then it's the second case: the calling app is specifically asking for the Gallery, not just for any app that can choose an image. Only the author of the calling app can fix this.