How to change size of item in TimelinePlot?

Question

How can one change the size of the markers in the TimelinePlot:

tp = {{2014, 12, 29} -> 
    ImageResize[ ExampleData[{"TestImage", "Lena"}], 600], {2015, 12, 
     14} -> ExampleData[{"TestImage", "Lena"}]};

TimelinePlot[tp, Spacings -> 10, AspectRatio -> 1/4, 
 AxesOrigin -> Center, PlotLayout -> "Grouped", 
 ImageSize -> {500, Automatic}, GridLines -> {Automatic, None}, 
 PreserveImageOptions -> True]

After checking all the options and examples in the documentation it's still unclear how to control this. I'm not sure if I should be using ImageResize, Items like in Grid, Tooltips, etc...

And simply using a Panel breaks everything:

Related:

• Problems with TimelinePlot
• how to make graphic timelines in mathematica

Answer 1

Both Panel and Pane work with just the PlotLayout option.

tpp = {{2014, 12, 29} -> 
    Pane@ImageResize[ExampleData[{"TestImage", "Lena"}], 700], {2015, 
     12, 14} -> ExampleData[{"TestImage", "Lena"}]};

TimelinePlot[tpp, PlotLayout -> "Grouped"]

However, something is odd as simply adding an empty string PlotLayout option (PlotLayout -> "") also works. Bug, perhaps?

Hope this helps.

version 10.3.1 on Win Pro 8.1 64bit