Placeholder does not allow paste from context menu

[lucharlesc]

Describe the issue

Text from the placeholder extension does not allow paste from the context menu on Chrome and Firefox. Safari does not appear to have this issue. Fix is possible by adding userSelect: "none" style to .cm-placeholder class via theme, but maybe this should be included by default by the extension in addition to the pointerEvents: "none" style here: https://github.com/codemirror/view/blob/main/src/placeholder.ts#L13.

Chrome

Context menu with "Paste" unavailable when right clicking on placeholder:

Context menu with "Paste" available when right clicking off placeholder:

Firefox

Context menu with "Paste" unavailable when right clicking on placeholder:

Context menu with "Paste" available when right clicking off placeholder:

Browser and platform

Chrome 134.0.6998.44, Firefox 136.0.3, macOS 15.2

Reproduction link

https://codemirror.net/try/#c=aW1wb3J0IHttaW5pbWFsU2V0dXAsIEVkaXRvclZpZXd9IGZyb20gImNvZGVtaXJyb3IiCmltcG9ydCB7cGxhY2Vob2xkZXJ9IGZyb20gIkBjb2RlbWlycm9yL3ZpZXciCgpuZXcgRWRpdG9yVmlldyh7CiAgZXh0ZW5zaW9uczogbWluaW1hbFNldHVwLmNvbmNhdChbCiAgICBwbGFjZWhvbGRlcigiUGxhY2Vob2xkZXIiKSwKICAgIEVkaXRvclZpZXcudGhlbWUoewogICAgICAiLmNtLXBsYWNlaG9sZGVyIjogewogICAgICAgIC8vIHVzZXJTZWxlY3Q6ICJub25lIiAvLyBVbmNvbW1lbnQgdGhpcyBsaW5lIHRvIGZpeCBvbiBDaHJvbWUgYW5kIEZpcmVmb3gKICAgICAgfQogICAgfSkKICBdKSwKICBwYXJlbnQ6IGRvY3VtZW50LmJvZHkKfSkK

[marijnh]

Thanks for finding a solution to this. Attached patch adds user-select: none to the placeholder's default style.