Here are some tips that you might find useful as you develop icons or other drawable assets:

• Android Icon Design Guidelines
• Choosing the Right Size and Format for Icons

Try to name files so that related assets will group together inside a directory when they are sorted alphabetically. In particular, it helps to use a common prefix for each icon type. For example:

ic_mixxx.ico

• Windows icon container. A full set should contain 16×16, 32×32, 48×48 and 256×256.
• Microsoft Vista+ Icons Guide

ic_mixxx.png mixxx-icon.png

• Note: Original name mixxx-icon.png restored since Linux seems not to like underscores for icon file names in .desktop files. This resulted in missing application icons on Gnome/KDE with mixxx.desktop .
• Application icon for Linux .desktop file . Primary size for application icons 48×48
• Desktop Entry Specification
• GNOME icon specification
• QT Desktop File Standard

ic_mixxx_window.png

• Window icon displayed in the corner of an application's top-level windows. Recommend size for Window icons 48×48
• Setting the application icon in QT 4

mixxx_install_logo.bmp

• Bitmap image to display on the header of installers pages for Windows NSIS installer. Recommended size 150×57.
• NSIS Modern UI Documentation

Sub-folder that holds all 48×48 *.png icons for display in Mixxx library widget

Sub-folder that holds all 48×48 *.png icons for display displayed in Mixxx preferences dialog

Sub-folder that holds various templates for image files

• ic_template_mixxx.svg = multilayered Inkscape template for Mixxx application icon, holds special layer for 16×16 icon too
• ic_template_library_and_preferences.svg = multilayered Inkscape vector template for all icons in library widget, preferences dialog & skins library style.
• ic_template_keyboard_mapping_sheet.svg = multilayered Inkscape vector template for keyboard mapping chart (for printout, documentation…)
• logo_mixxx.svg = multilayered Inkscape vector template for Mixxx logo (holds bw variant too)
• logo_mixxx.png = Mixxx logo bitmap
• skin_template_outline.svg = multilayered Inkscape vector template for Outline skin. See Creating Skins.

application.icns

• Apple icon container for display in in Mixxx` *.app bundles for OS X.
• A full set should contain 16×16, 32×32, 128×128,256×256 and 512×512
• Apple Human Interface Guidelines

VolumeIcon.icns

• Apple icon container for display in Mixxx` *.dmg images for OS X.
• A full set should contain 16×16, 32×32, 128×128 ( 128 is maximum size OS X desktop grid, enough for dmg`s)

holds all the unused files lurking for some reasons in mixxx/res/images/ until