Always overlap modebar with hoverlabels

[Braintelligence]

Hi there, it would be awesome if we could avoid this:

No matter if I put the modebar to orientation = v or h hoverlabels on the right side will land behind the modebar and thus be hard to read. Especially bad for narrow displays.

I tried to make the modebar only appear on hover as demonstrated in some issues/PRs but I couldn't find such an option.

Other than that I can't think of a situation where you'd not want hoverlabels to always overlap the modebar.

[etpinard]

Thanks for the report!

What's the best solution here in your mind? Show the hover labels above the mode bar (but then the modebar wouldn't be accessible). Show the hover labels on the other side of the data points (on your graph, that's to the left)?

In the meantime, I suggest increasing the right margin layout.margin.r so that both the modebar and the hover labels fit on the right-hand side of your graph.

[alexcjohnson]

(but then the modebar wouldn't be accessible)

But that's only when the mouse is over the data anyway, right? Hover labels will disappear when you mouse off the plot and onto the modebar, won't they?

Seems like this may require a third top-level <svg> element just for hover labels... but I agree that putting them in front of everything else is the ideal behavior.

[etpinard]

But that's only when the mouse is over the data anyway, right?

What happens if one hovers over a hover label that sits outside the subplot domain? I think the hover labels stays, but I'd have to check.

[alexcjohnson]

Pretty sure hover labels themselves don't interact with the mouse at all... hovering over the label, whether it's on or off the subplot, does nothing to keep it from disappearing if the mouse isn't in range of the associated data point/object.

[etpinard]

There's this block:

plotly.js/src/plots/cartesian/graph_interact.js

Lines 139 to 142 in 1aa6c85

	hoverLayer.onmousemove = function(evt) {
	evt.target = gd._fullLayout._lasthover;
	Fx.hover(gd, evt, fullLayout._hoversubplot);
	};

but yeah I'm not sure it actually does anything.

[alexcjohnson]

If anything that block is what ensures we pass the event on to the subplot rather than the hover label keeping it. But yeah, in principle if the hover labels are created correctly this shouldn't be necessary.

[Braintelligence]

Thank you guys for your quick and considerable replies.

I'd prefer having an almighty everything-overlapping hoverlabel.

Adding left or right margins is a no-go because I need the full width that I can get for 360px wide displays. 😭

[antoinerg]

I'm not sure what's the best way to solve this. The modebar is a div so it's not going to respect the order of drawing of SVG. I could, however, add a CSS z-index to both the modebar div and the top layer SVG and make sure the latter is larger. Would that be satisfactory?

modebar has z-index: 1001 which is why it wouldn't respect order of drawing.

[etpinard]

modebar has z-index: 1001 which is why it wouldn't respect order of drawing.

Hmm, right. This is annoying. Maybe we should start thinking seriously about moving the modebar buttons into

aka fullLayout._toppaper along side <g.hoverlayer> and draw them purely in SVG. This would allow us to 🔪 the numerous Lib.addRelatedStyleRule calls in modebar/modebar.js.

[antoinerg]

@etpinard Another solution is to remove that z-index on the modebar container and to order it properly with the other DOM elements. To resolve the current issue, we could place a third SVG element containing the hoverlabels which would be drawn above modebar. If you are open to this idea, I could add it to PR #3500

[anders-kiaer]

A related Dash issue, if relevant here as well:
https://community.plot.ly/t/modebar-appears-on-top-of-dropdown-list/6398

To reproduce:

import dash
import dash_html_components as html
import dash_core_components as dcc

app = dash.Dash(__name__)
app.layout = html.Div([
    dcc.Dropdown(
        id='my-dropdown',
        options=[
            {'label': 'New York City', 'value': 'NYC'},
            {'label': 'Montreal', 'value': 'MTL'},
            {'label': 'San Francisco', 'value': 'SF'}
        ],
        value='NYC'
    ),
    dcc.Graph(
        id='example-graph',
        figure={
            'data': [
                {'x': [1, 2, 3], 'y': [4, 1, 2], 'type': 'bar', 'name': 'SF'},
                {'x': [1, 2, 3], 'y': [2, 4, 5], 'type': 'bar', 'name': u'Montréal'},
            ],
            'layout': {
                'title': 'Dash Data Visualization'
            }
        }
    )
])

if __name__ == '__main__':
    app.run_server(debug=True)

[antoinerg]

Thank you @anders-kiaer for reporting this issue! I think your issue and the one originally described here are related. In your Dash app, the mode bar appears over the selection menu because its z-index is set to 1001. We shouldn't rely on this CSS style to make the mode bar appear above other elements but instead, we should draw it in the right order.