По-моему это редактируется в файле: itg.flat.dark.sublime-theme
{
"class": "tab_control",
"attributes": ["selected"],
"layer0.tint": [255, 255, 255, 200]
},
{
"class": "tab_label",
"parents": [{"class": "tab_control", "attributes": ["selected"]}],
"fg": [91, 84, 81, 255],
"font.bold" : false
},
{
"class": "tab_control",
"attributes": ["hover"],
"layer0.tint": [255, 255, 255, 180]
},
{
"class": "tab_label",
"parents": [{"class": "tab_control", "attributes": ["hover"]}],
"fg": [91, 84, 81, 255],
"font.bold" : false
},