取消選擇一些選項

				
					{"blocks":"<xml xmlns=\"https://developers.google.com/blockly/xml\"><variables><variable>mainLayout</variable><variable>mainScreen</variable><variable>optionList</variable><variable>resultButton</variable></variables><block type=\"pxt-on-start\" x=\"0\" y=\"0\"><statement name=\"HANDLER\"><block type=\"variables_set\"><field name=\"VAR\">mainLayout</field><value name=\"VALUE\"><shadow type=\"math_number\"><field name=\"NUM\">0</field></shadow><block type=\"ScreenItem_createLayout\"/></value><next><block type=\"variables_set\"><field name=\"VAR\">mainScreen</field><value name=\"VALUE\"><shadow type=\"math_number\"><field name=\"NUM\">0</field></shadow><block type=\"Screen_create\"><value name=\"label\"><shadow type=\"text\"><field name=\"TEXT\">Main</field></shadow></value><value name=\"layout\"><block type=\"variables_get\"><field name=\"VAR\">mainLayout</field></block></value></block></value><next><block type=\"variables_set\"><field name=\"VAR\">optionList</field><value name=\"VALUE\"><shadow type=\"math_number\"><field name=\"NUM\">0</field></shadow><block type=\"Control_createOptionList\"><mutation xmlns=\"http://www.w3.org/1999/xhtml\" _expanded=\"2\" _input_init=\"true\"></mutation><value name=\"isMultiple\"><shadow type=\"logic_boolean\"><field name=\"BOOL\">TRUE</field></shadow></value><value name=\"options\"><block type=\"lists_create_with\"><mutation items=\"3\" horizontalafter=\"3\"/><value name=\"ADD0\"><shadow type=\"text\"><field name=\"TEXT\">a</field></shadow></value><value name=\"ADD1\"><shadow type=\"text\"><field name=\"TEXT\">b</field></shadow></value><value name=\"ADD2\"><shadow type=\"text\"><field name=\"TEXT\">c</field></shadow></value></block></value></block></value><next><block type=\"ScreenItem_Layout_add\"><value name=\"this\"><block type=\"variables_get\"><field name=\"VAR\">mainLayout</field></block></value><value name=\"item\"><block type=\"variables_get\"><field name=\"VAR\">optionList</field></block></value><next><block type=\"variables_set\"><field name=\"VAR\">resultButton</field><value name=\"VALUE\"><shadow type=\"math_number\"><field name=\"NUM\">0</field></shadow><block type=\"Control_createButton\"><value name=\"content\"><shadow type=\"text\"><field name=\"TEXT\">Show Result</field></shadow></value></block></value><next><block type=\"ScreenItem_Layout_add\"><value name=\"this\"><block type=\"variables_get\"><field name=\"VAR\">mainLayout</field></block></value><value name=\"item\"><block type=\"variables_get\"><field name=\"VAR\">resultButton</field></block></value><next><block type=\"ScreenItem_ScreenItem_onClick\"><value name=\"this\"><block type=\"variables_get\"><field name=\"VAR\">resultButton</field></block></value><statement name=\"HANDLER\"><block type=\"Control_OptionList_selectOptions\"><value name=\"this\"><block type=\"variables_get\"><field name=\"VAR\">optionList</field></block></value><value name=\"options\"><block type=\"lists_create_with\"><mutation items=\"2\" horizontalafter=\"3\"/><value name=\"ADD0\"><shadow type=\"text\"><field name=\"TEXT\">a</field></shadow></value><value name=\"ADD1\"><shadow type=\"text\"><field name=\"TEXT\">b</field></shadow></value></block></value></block></statement></block></next></block></next></block></next></block></next></block></next></block></next></block></statement></block></xml>"}