Using Submine test 3, build 3083 on windows 7.
Currently using Dawn.tm theme, selected from Preferences->Color themes
The only problem
In your user folder you can override the themes properties you want. In this case there is a minor problem as the scrollbar texture (the image that contains the scrollbar with the top and bottom semicircles) is quite dark, so although you modify the tint you can't get a light color similar to white unless you change that texture (image).
So the solution I pruposse is to create two new images (horizontal and vertical scrollbar) that are lighter, set it in the theme preference overrides and then (optionally) set the tint color you want.
and scroll_puck_horiz.png
.Inside theme_override, create a file with the name of your theme. If you are using the default theme the file should be named Default.sublime-theme. If you are not using the default theme you can see the name of the theme you are using in Settings>Preferences>theme, and then create a file with that name (for example Material-Theme-Darker.sublime-theme) inside theme_override Inside this new file place the following content:
[
// More visible scrollbar
{
"class": "puck_control",
"layer0.texture": "User/theme_override/scroll_puck.png",
// Optional: set to your desired RGB color
"layer0.tint": [40, 170, 250],
"layer0.opacity": 1.0,
"layer1.opacity": 0.0,
"layer0.inner_margin": 2
},
{
"class": "puck_control",
"attributes": ["horizontal"],
"layer0.texture": "User/theme_override/scroll_puck_horiz.png"
}
]
Restart sublime text
EDIT: this is the result

EDIT: added basic info for people that are not using the default theme.
Note: if you are not using the default theme the results might change depending on the values that your theme overrides. If you want to know what values your theme is using, and you want to customize them, you can see them inside the .sublime-package file of your theme. For example, if you are using Material Theme open Material Theme.sublime-package (this is just a zip file) and inside there will be a file called Material-Theme-Darker.sublime-theme, you should not modify this file, but you can customize/override whatever you want using the file we have created in step 4.