Selecting items in a diagram is important when you want to do something with them. For example, move a node about, change some property of an edge, or edit a label.
yEd offers different ways to select all or only specific nodes, edges, labels, or bends in a diagram. Even in situations where diagram elements are on top of each other and overlapping, there is an easy way to cycle through them.
Creating a Selection with the Mouse
Easy things first: Creating a single-element selection
Selecting elements with the mouse is quite easy. With a single left-click on a node or the path of an edge, the corresponding element gets selected.
Generally, the same is true for labels also, however, in the case of node labels, which are often completely within the bounds of their nodes, or edge labels that are at the same position, you need to cycle through the stacked elements as described below.
Selecting a bend of an edge path is also possible by clicking on it, however, it might be easier to select it using the selection rectangle aka marquee selection.
Note that selecting an element using single mouse click clears the existing selection, in other words, any previously selected elements get unselected.
Creating a multi-element selection
By left-dragging the mouse within the editor window (i.e., left-clicking somewhere in the editor window, then moving the mouse while keeping the mouse button pressed, and finally releasing the mouse button), you create a marquee selection and select all diagram elements of the same kind that are within the rectangle.
Note that while you are left-dragging the mouse, the marquee selection is indicated by a selection rectangle, the "marquee."
By default, i.e. without some additional preparations/precautions (see below), the marquee can actually only be used to select multiple nodes and/or bends. (Note that bends are considered to be like nodes in this respect.)
Selecting multiple edges using the marquee
To select multiple edges of the diagram, you need to first select a single edge, and then use the marquee.
Creating a multi-element selection is also possible when Shift-clicking (i.e., pressing the Shift key while left-clicking) elements of the same kind. This is the same as extending an existing selection.
Selecting all Elements of a Kind
Using the keyboard short-cut Control-A [Command-A on Mac], you can select all nodes of the diagram in the current editor window. Note that also all bends will be selected at the same time, since bends are considered to be "just like nodes" in this respect.
To select all edges of the diagram, you need to first select an arbitrary edge, and then use Control-A [Command-A on Mac]. In a similar manner you can select all node labels, and all edge labels, respectively.
Extending an Existing Selection
To extend an existing selection you can Shift-left-click (i.e., pressing the Shift key while left-clicking) elements of the same kind. The corresponding element gets selected.
Cycling Through Elements that are Overlapping
When elements of the diagram are overlapping each other, it is often difficult to select the proper item. By Control-left-clicking [Alt-left-clicking on Mac] (i.e., pressing the Control [Alt on Mac] key while left-clicking) on the elements, you can "cycle" through all of them one after the other until you reach the proper item.
Other Ways of Selecting Elements
You can also select nodes by clicking on their entry in the tree-like presentation of the diagram in the Structure View. The Structure View also allows to select multiple nodes:
By Shift-left-clicking on two distinct entries, you define a range between them in the tree that selects the corresponding nodes in the editor window.
Control-left-clicking on any entry in the tree adds the corresponding node to the existing selection in the editor window.
The "Current Elements" in the Palette shows all different elements in the editor window. In the context menu of an element you can choose the command "Select Matching Elements."
The Selector tool, which is available under the Tools menu, can be used to conveniently select elements according to a variety of properties, e.g., graphical properties (fill color, line color) and structural properties (number of connecting edges, incoming edges, outgoing edges).
Also, you can select elements based on the text of their label.