docs: a bit more detail for RGBA sequences

refs: https://github.com/wez/wezterm/issues/2313

docs/changelog.md

@@ -51,7 +51,7 @@ As features stabilize some brief notes about them will accumulate here.
 * Internal scrollback datastructure improvements reduce per-cell overhead by up to ~40x depending on the composition of the line (lines with lots of varied attributes or image attachments will have more overhead).
 * Improved search performance
 * Quickselect: now defaults to searching 1000 lines above and below the current viewport, making it faster and the labels shorter for users with a larger scrollback. A new `scope_lines` parameter to [QuickSelectArgs](config/lua/keyassignment/QuickSelectArgs.md) allows controlling the search region explicitly. Thanks to [@yyogo](https://github.com/yyogo) for the initial PR! [#1317](https://github.com/wez/wezterm/pull/1317)
-* OSC 10, 11 and 12 (Set Default Text Background, Default Text Foreground Color, and Text Cursor Color) now support setting the alpha component [#2313](https://github.com/wez/wezterm/issues/2313)
+* OSC 10, 11 and 12 (Set Default Text Background, Default Text Foreground Color, and Text Cursor Color) now support setting the alpha component [#2313](https://github.com/wez/wezterm/issues/2313), and added [CSI 38:6](escape-sequences.md#csi-386---foreground-color-rgba), `CSI 48:6` and `CSI 58:6` extensions to allow setting full color RGB with Alpha channel for spans of text.
 * Copy Mode: setting the same selection mode a second time will now toggle off that mode and clear the selection, preserving the current position [#2246](https://github.com/wez/wezterm/discussions/2246)
 * Copy Mode: new default vim-style `y` "yank" key assignment will copy the selection and close copy mode
 

docs/escape-sequences.md

@@ -225,6 +225,8 @@ is unambiguous and should be preferred; the semicolon form should not be used
 by new applications and is not documented here in the interest of avoiding
 accidental new implementations.
 
+##### CSI 38:5 - foreground color palette index
+
 This sequence will set the *foreground color* to the specified palette INDEX,
 which can be a decimal number in the range `0-255`.
 
@@ -232,6 +234,8 @@ which can be a decimal number in the range `0-255`.
 CSI 38 : 5 : INDEX m
 ```
 
+##### CSI 48:5 - background color palette index
+
 This sequence will set the *background color* to the specified palette INDEX,
 which can be a decimal number in the range `0-255`.
 
@@ -239,6 +243,8 @@ which can be a decimal number in the range `0-255`.
 CSI 48 : 5 : INDEX m
 ```
 
+##### CSI 58:5 - underline color palette index
+
 This sequence will set the *underline color* to the specified palette INDEX,
 which can be a decimal number in the range `0-255`.
 
@@ -246,6 +252,8 @@ which can be a decimal number in the range `0-255`.
 CSI 58 : 5 : INDEX m
 ```
 
+##### CSI 38:2 - foreground color: RGB
+
 This sequence will set the *foreground color* to an arbitrary color in RGB
 colorspace.  The `R`, `G` and `B` symbols below are decimal numbers in the
 range `0-255`.  Note that after the `2` parameter two colons are present; its
@@ -265,6 +273,19 @@ ID argument is not specified:
 CSI 38 : 2 : R : G : B m
 ```
 
+##### CSI 38:6 - foreground color: RGBA
+
+*Since: nightly builds only*
+
+This is a wezterm extension: wezterm considers colorspace ID `6` as RGBA,
+allowing you to specify the alpha channel in addition to the RGB channels.
+
+```
+CSI 38 : 6 : : R : G : B : A m
+```
+
+##### CSI 48:2 - background color: RGB
+
 This sequence will set the *background color* to an arbitrary color in RGB colorspace.
 The `R`, `G` and `B` symbols below are decimal numbers in the range `0-255`:
 
@@ -280,6 +301,19 @@ ID argument is not specified:
 CSI 48 : 2 : R : G : B m
 ```
 
+##### CSI 48:6 - background color: RGBA
+
+*Since: nightly builds only*
+
+This is a wezterm extension: wezterm considers colorspace ID `6` as RGBA,
+allowing you to specify the alpha channel in addition to the RGB channels.
+
+```
+CSI 48 : 6 : : R : G : B : A m
+```
+
+##### CSI 58:2 - underline color: RGB
+
 This sequence will set the *underline color* to an arbitrary color in RGB colorspace.
 The `R`, `G` and `B` symbols below are decimal numbers in the range `0-255`:
 
@@ -295,6 +329,17 @@ ID argument is not specified:
 CSI 58 : 2 : R : G : B m
 ```
 
+##### CSI 58:6 - underline color: RGBA
+
+*Since: nightly builds only*
+
+This is a wezterm extension: wezterm considers colorspace ID `6` as RGBA,
+allowing you to specify the alpha channel in addition to the RGB channels.
+
+```
+CSI 58 : 6 : : R : G : B : A m
+```
+
 #### Cursor Movement
 
 #### Editing Functions
@@ -345,9 +390,9 @@ The table below is keyed by the OSC code.
 |7  |Set Current Working Directory | [See Shell Integration](shell-integration.html#osc-7-escape-sequence-to-set-the-working-directory) ||
 |8  |Set Hyperlink | [See Explicit Hyperlinks](hyperlinks.html#explicit-hyperlinks) | |
 |9  |iTerm2 Show System Notification | Show a "toast" notification | `printf "\e]9;%s\e\\" "hello there"` |
-|10 |Set Default Text Foreground Color| | `\x1b]10;#ff0000\x1b\\` |
-|11 |Set Default Text Background Color| | `\x1b]11;#0000ff\x1b\\` |
-|12 |Set Text Cursor Color| | `\x1b]12;#00ff00\x1b\\` |
+|10 |Set Default Text Foreground Color| | `\x1b]10;#ff0000\x1b\\`.<br/> Also supports RGBA in nightly builds: `printf "\e]10;rgba(127,127,127,0.4)\x07"` |
+|11 |Set Default Text Background Color| | `\x1b]11;#0000ff\x1b\\`.<br/> Also supports RGBA in nightly builds: `printf "\e]11;rgba:efff/ecff/f4ff/d000\x07"` |
+|12 |Set Text Cursor Color| | `\x1b]12;#00ff00\x1b\\`.<br/> Also supports RGBA in nightly builds. |
 |52 |Manipulate clipboard | Requests to query the clipboard are ignored. Allows setting or clearing the clipboard | |
 |104|ResetColors | Reset color palette entries to their default values | |
 |133|FinalTerm semantic escapes| Informs the terminal about Input, Output and Prompt regions on the display | [See Shell Integration](shell-integration.html) |