Is there an easier way to select components/groups that are behind another geometry? or inside one?
Is there a way to transfer a component from one group to another?
Yes there is. Welcome the Outliner window.
This tutorial refers to components in your model, but in this case, groups behave in the exact same manner.
If not yet visible, click ”Window → Outliner” to see this window in Sketchup.
The Outliner window shows you a list of all components and groups in your model in a tree view – meaning, each sub component is shown within it’s container (parent) component/group so that it’s easy to make the parts that make the whole (think legs and top components within a table component/group)
One thing that is convenient with using the Outliner window, is that you can select components and sub components directly – without having to visually “aim” and clicking them – simply click the component name in the Outliner window, and it will be selected – even if it’s inside a different component/group. Double click it in the Outliner Window – and you’re in Component Edit mode! in a Snap!
Another powerful usage of the Outliner window is the ability to move sub-components from one group to another.
As shown in the following picture, the label on this model is a component within the model’s parent component. if you move the model, the label moves with it (as it is contained within it and is part of it):
By selecting the label sub-component and dragging it outside the model’s component in the Outliner Window we are literally taking it out of the model’s component, and making it a free stand-alone component, if we will now move the model’s component – the label will not move with it as it is no longer part of the model’s component:
This way you can easily navigate through your components (another great excuse/reason to use components in Sketchup) and sub components, without having to rely on your angle of view, hiding other components that are in the way, or having to “copy-paste” with exact positioning to move components from one container to another.
-- ㊍ When in doubt - There is no doubt - Go the safer route.