To copy your desired content or copy your PDF page in view as searchable text to Windows clipboard is easy.
Basically we have four methods to to copy your desired content to Windows clipboard as searchable text.
Method A: Press Ctrl+C on your keyboard
Method B: Click the Copy as text button 
on the tool bar
Method C: From the main menu, Copy->Copy as text
Method D: Right-click your PDF page to pop up the quick menu and choose Copy as text
Here is an example to copy the current PDF page (PDF page in view) to Windows clipboard as searchable text.
1) Open a PDF file, and navigate to a page
2) Copy Text using any of the methods given above
3) Switch to a word processor program, and Paste. (If you don't have a word processor program at hand, use Windows Notepad program instead)
What do you see? All text on your PDF page is now copied to Windows clipboard, and pasted to your word processor program.
Here is another example to copy a portion of a PDF page,
1) Use the cropping tool to draw a rectangle area from top-left to bottom-right to include your desired content.
In this example, the desired content is the paragraph beginning with The "recent" panel of the Office Hub provides quick access to ...
2) Press Ctrl+X (or click the Copy as image button 
on the tool bar, or go to the menu Copy->Copy as image)
3) Switch to a word processor program, and Paste. (If you don't have a word processor program at hand, use Windows Notepad program instead)
What is the outcome? Your desired text (in this example, it is the paragraph) is now copied to your Windows clipboard, and pasted into your word processor.
The quick menu (i.e. the right-click menu) in the above illustration is for demo purpose only. In this example, as long as you have a rectangle area, a right-click on your mouse definitely cancels the rectangle area.
Note: Method A, B, C work in all circumstances. Method D works only when you copy your current PDF page in view as an image to Windows clipboard. If you are to copy a portion of your PDF page, avoid using Method D.