v0.2.1

• Compatible with lower versions of dart #98
• [macos & windows] Add resized, moved events. #28
• [linux] Implement getTitleBarHeight metnod #49
• [linux] Implement getOpacity metnod #44
• Add TitleBarStyle enum #99
• [linux] Implement setAlwaysOnBottom method #100
• [windows] Removes crazy jittering when resizing window #103
• [windows] Fix overflow on fullscreen and maximize #105
• [windows] Implement setHasShadow and hasShadow methods #110
• [windows] Fix setAlignment(Alignment.bottomRight) display position is not correct #112 #113