* Add error message boxes * Improve performance when editing a large image * Improve flood fill performance * Fix visual glitches during window creation * Fix crash when loading palette-based PNG files (automatically converted to 32-bit for now) * Add dedicated save as-button and display file name in window title * Add about dialog * Active selection is now visible in the preview widget * Compress undo/redo-steps for much lower memory usage * Add distinct blend modes replace and alpha blend