fix: installer not interrupted when system version not fit (>=Windows…

… 8.1)

output/install.nsi

@@ -73,6 +73,7 @@ LangString LNKFORUPDATER ${LANG_TRADCHINESE} "【小狼毫】檢查新版本"
 LangString LNKFORSETUP ${LANG_TRADCHINESE} "【小狼毫】安裝選項"
 LangString LNKFORUNINSTALL ${LANG_TRADCHINESE} "卸載小狼毫"
 LangString CONFIRMATION ${LANG_TRADCHINESE} "安裝前，請先卸載舊版本的小狼毫。$\n$\n按下「確定」移除舊版本，按下「取消」放棄本次安裝。"
+LangString SYSTEMVERSIONNOTOK ${LANG_TRADCHINESE} "您的系统不被支持，最低系統要求:Windows 8.1!"
 
 !insertmacro MUI_LANGUAGE "SimpChinese"
 LangString DISPLAYNAME ${LANG_SIMPCHINESE} "小狼毫输入法"
@@ -88,6 +89,7 @@ LangString LNKFORUPDATER ${LANG_SIMPCHINESE} "【小狼毫】检查新版本"
 LangString LNKFORSETUP ${LANG_SIMPCHINESE} "【小狼毫】安装选项"
 LangString LNKFORUNINSTALL ${LANG_SIMPCHINESE} "卸载小狼毫"
 LangString CONFIRMATION ${LANG_SIMPCHINESE} '安装前，请先卸载旧版本的小狼毫。$\n$\n点击 "确定" 移除旧版本，或点击 "取消" 放弃本次安装。'
+LangString SYSTEMVERSIONNOTOK ${LANG_SIMPCHINESE} "您的系統不被支持，最低系统要求:Windows 8.1!"
 
 !insertmacro MUI_LANGUAGE "English"
 LangString DISPLAYNAME ${LANG_ENGLISH} "Weasel"
@@ -103,10 +105,19 @@ LangString LNKFORUPDATER ${LANG_ENGLISH} "Weasel Check for Updates"
 LangString LNKFORSETUP ${LANG_ENGLISH} "Weasel Installation Preference"
 LangString LNKFORUNINSTALL ${LANG_ENGLISH} "Uninstall Weasel"
 LangString CONFIRMATION ${LANG_ENGLISH} "Before installation, please uninstall the old version of Weasel.$\n$\nPress 'OK' to remove the old version, or 'Cancel' to abort installation."
+LangString SYSTEMVERSIONNOTOK ${LANG_ENGLISH} "Your system not supported, minimium system required: Windows 8.1!"
 
 ;--------------------------------
 
 Function .onInit
+  ; if not version >= 8.1, quit and MessageBox(if not silent)
+  ${IfNot} ${AtLeastWin8.1}
+    IfSilent toquit
+    MessageBox MB_OK '$(SYSTEMVERSIONNOTOK)'
+toquit:
+    Quit
+  ${EndIf}
+
   ReadRegStr $R0 HKLM "Software\Rime\Weasel" "InstallDir"
   StrCmp $R0 "" 0 skip
   ; The default installation directory