I just tried out the “forcedROMode” described in the docs in the ActionButtons section.
While implementing a “RO-Toggle” command, my demand came up: I’d like to edit the Action-Buttons “on-the-fly” to change a button/icon to represent the current status.
Would be nice, if the “actionbutton.define” function would get an “actionbutton.update” equivalent 
(or maybe an “actionbutton.delete” to remove a button to create it new)
Dont’t know, if changing buttons at runtime is possible, anyway…
How about something like this:
actionButton.define {
icon = (editor.getUiOption("forcedROMode") and "eye-off") or "eye",
run = function()
local mode = editor.getUiOption("forcedROMode")
editor.setUiOption("forcedROMode", not mode)
editor.rebuildEditorState()
editor.reloadConfigAndCommands()
end
}
Sounds great. Good Idea, i will try that as soon as possible
It works, thanks!
The only thing that the top bar mini-editor does not reflect the mode. It would be nice if it also can be turned to read only mode somehow. Any ideas?
Tried it and it works like a charm! Thanks again!
In fact, that basically is exactly what I tried to achieve.
The puzzle piece I was missing obviously is the “actionbutton.define” function.
Until now I used the "config.set { actionbuttons = … } definition.
And thanks for the idea to simply reload the config/UI. Did not see the forest for the trees here… 
Only thing I have to figure out now is how to define the position of the button, as via “actionbuttons.define”, the button is placed at the end (which is only a cosmetic issue for me…)
Glad that worked 
Looking at the implementation, the config.set { actionbuttons = ... } method should still work, as actionbutton.define is just a wrapper for that. I think what’s changed is that instead of the command key you’d use the run key with a function value. That way you can still control the order in wich the buttons are placed. Didn’t try that yet though.
Don’t think there’s a build-in way, but I found a way to do it with dom-manipulation:
js.window.document.querySelector(".sb-mini-editor .cm-content").contentEditable = false
What I ended up with:
local ro = editor.getUiOption("forcedROMode")
actionButton.define {
mobile = true,
icon = (ro and "edit2") or "eye",
run = function()
local cursor = editor.getCursor()
editor.setUiOption("forcedROMode", not ro)
editor.rebuildEditorState()
editor.reloadConfigAndCommands()
js.window.document.querySelector(".sb-mini-editor .cm-content").contentEditable = ro
editor.moveCursor(cursor, true)
end
}
This is for the CONFIG if somebody needs it…
```space-lua
config.set {
actionButtons = {
-- some buttons
{
-- mobile: true,
icon = editor.getUiOption('forcedROMode') and 'edit' or 'eye',
run = function()
local ro = editor.getUiOption('forcedROMode')
local cur = editor.getCursor()
editor.setUiOption('forcedROMode', not ro)
editor.rebuildEditorState()
editor.reloadConfigAndCommands()
js.window.document.querySelector('.sb-mini-editor .cm-content').contentEditable = ro
editor.moveCursor(cur, true)
end,
description = 'Toggle read-only mode'
},
-- other buttons
}
```
The mobile: true causes it will apply on mobile device only and the button will be invisible on non-mobile device.
Thanks a lot!! This is great!!
This way it is even possible to define the positions of the icons.
Some support for ordering is needed for actionButton.define{}. I’ve no time to inspect now, but perhaps there is some already. It would be weird a little to not allow ordering of the buttons in the first plan.
UPDATE Of course there IS the priority already!
Example:
actionButton.define {
priority = 1000,
-- the rest
}
priority(optional): determines priority of button (the higher, the earlier in the list)
Also see Library/Std/Action Button.md.
This is a pro and a con of silverbullet.md at the same time.
It has so many hidden gems!
Sometimes you only have to find them
(And sometimes you have to have the idea to search for them in the first place )
I found one more thing that should not be “editable” in read-only mode. Tasks can still be clicked and edited. 
(I hit this one accidentaly while on mobile where I use this primarily.)
Also, it would be nice if we can hide the edit icon for ${} queries.
Anything else? It will be splendid if we hack all of this together to achieve truly safe read-only mode to be used while rumbling on public transportation vehicles, won’t it?
Well, from my point of view I like it exacty the way it is now.
For example:
I write my shopping list to a note at home. Then I switch to readonly.
Later in the shop I can still check my purchased items, but it prevents editing of the list itself.
Before I discovered readonly, I had several times, that I deleted some text by mistake instead of checking.
So, we might need two different read-only modes
I destroyed many things historicaly while using SB in weird and rushy situations that I would rather be safe on mobile. Just looking for a way to do it. The effort is also worth as example of what can be done using the more advanced APIs. And, it’s just a Lua function in the end. Put whatever suit you best in it. 
So I extended this with all of the above and some extra features like persistence, and made it easily configurable. You can now also (optionally):
This is what I’ve got now and it works great!
-- Must be set before actionButtons
config.set {
readOnly = {
mobileOnlyActionButton = false,
disableCheckboxes = true,
shortcut = 'Ctrl-alt-t',
persistent = true,
enabledIcon = 'edit',
disabledIcon = 'eye'
}
}
config.set {
actionButtons = {
-- Your other action buttons here...
{
mobile = config.get('readOnly').mobileOnlyActionButton,
icon = editor.getUiOption("forcedROMode") and config.get('readOnly').enabledIcon or config.get('readOnly').disabledIcon,
description = editor.getUiOption("forcedROMode") and "Enable edit mode" or "Enable read-only mode",
run = function()
editor.invokeCommand("Toggle Read-Only Mode")
end
}
}
}
--
-- Read-only mode implementation
function toggleReadOnlyMode()
local cursor = editor.getCursor()
local mode = editor.getUiOption('forcedROMode')
editor.setUiOption('forcedROMode', not mode)
editor.rebuildEditorState()
editor.reloadConfigAndCommands()
js.window.document.querySelector('.sb-mini-editor .cm-content').contentEditable = mode
if config.get('readOnly').persistent then
clientStore.set('readOnly', not mode)
end
if mode == false and config.get('readOnly').disableCheckboxes then
js.window.document.head.insertAdjacentHTML('beforeend',
'<style id="readonly-checkbox-css">' ..
'.sb-checkbox input[type="checkbox"] { pointer-events: none; cursor: default; opacity: 0.5; }' ..
'</style>'
)
else
checkbox_css = js.window.document.getElementById('readonly-checkbox-css')
if checkbox_css ~= nil then
checkbox_css.remove()
end
end
editor.moveCursor(cursor, true)
end
command.define {
name = 'Toggle Read-Only Mode',
key = config.get('readOnly').shortcut,
run = function()
toggleReadOnlyMode()
end
}
event.listen {
name = 'system:ready',
run = function(e)
if config.get('readOnly').persistent
then
local readOnlyConfig = clientStore.get('readOnly')
local readOnlyCurrent = editor.getUiOption('forcedROMode')
if readOnlyConfig and not readOnlyCurrent then
toggleReadOnlyMode()
end
end
end
}