[ListItemSecondaryAction] visibility on hover

• I have searched the issues of this repository and believe that this is not a duplicate.

Expected Behavior

ListItemSecondaryAction should be able to be hidden by default, then visible on hover. This is a really common use case, so if possible, we should consider a clean way to make this (optional) behavior available behind a boolean property.

Current Behavior

When implemented with css sibling selectors and hovering over the secondary action, the icon blinks continuously. When hovered anywhere else on the ListItem, the blinking stops and works as expected.

Steps to Reproduce (for bugs)

Using css sibling selector (shown above): https://codesandbox.io/s/xo0mmyv2oo

Context

Secondary actions visible for larger lists (e.g. Google contacts list) can be overwhelming. Hiding icons until hovered is a common way to declutter user interfaces.

Your Environment

Tech	Version
Material-UI	1.0.0-beta.33
React	16.2.0
browser	Chrome

Any guidance @oliviertassinari @kof as to what the root cause of blinking?

[oliviertassinari]

import React from "react";
import PropTypes from "prop-types";
import { withStyles } from "material-ui/styles";
import List, {
  ListItem,
  ListItemSecondaryAction,
  ListItemText
} from "material-ui/List";
import Checkbox from "material-ui/Checkbox";
import IconButton from "material-ui/IconButton";
import CommentIcon from "material-ui-icons/Comment";

const styles = theme => ({
  root: {
    width: "100%",
    maxWidth: 360,
    backgroundColor: theme.palette.background.paper
  },
  listItemSecondaryAction: {
    visibility: "hidden"
  },
  listItem: {
    border: "1px solid blue",
-   "&:hover ~ $listItemSecondaryAction": {
+   "&:hover $listItemSecondaryAction": {
      border: "1px solid green",
      visibility: "inherit"
    }
  }
});

class CheckboxList extends React.Component {
  state = {
    checked: [0]
  };

  handleToggle = value => () => {
    const { checked } = this.state;
    const currentIndex = checked.indexOf(value);
    const newChecked = [...checked];

    if (currentIndex === -1) {
      newChecked.push(value);
    } else {
      newChecked.splice(currentIndex, 1);
    }

    this.setState({
      checked: newChecked
    });
  };

  render() {
    const { classes } = this.props;

    return (
      <div className={classes.root}>
        <List>
          {[0, 1, 2, 3].map(value => (
            <ListItem
              key={value}
              dense
              button
              onClick={this.handleToggle(value)}
-             className={classes.listItem}
+             classes={{
+               container: classes.listItem
+             }}
            >
              <Checkbox
                checked={this.state.checked.indexOf(value) !== -1}
                tabIndex={-1}
                disableRipple
              />
              <ListItemText primary={`Line item ${value + 1}`} />
              <ListItemSecondaryAction
                className={classes.listItemSecondaryAction}
              >
                <IconButton aria-label="Comments">
                  <CommentIcon />
                </IconButton>
              </ListItemSecondaryAction>
            </ListItem>
          ))}
        </List>
      </div>
    );
  }
}

CheckboxList.propTypes = {
  classes: PropTypes.object.isRequired
};

export default withStyles(styles)(CheckboxList);

https://codesandbox.io/s/l3n2nwpzq7

[rosskevin]

Awesome thanks @oliviertassinari. I couldn’t get your url to load your changes so I forked it in case anyone else runs across it - https://codesandbox.io/s/649v7kozm3

Thanks again for taking a look.